Use of proline specific endoproteases to hydrolyse peptides and proteins

ABSTRACT

The present invention relates to a process for the proteolytic hydrolysis of a peptide or a polypeptide, said peptide or polypeptide comprising 4 to 40, preferably 5 to 35, amino acid residues and said peptide or polypeptide is not hydrolysable by subtilisin whereby said peptide or polypeptide is hydrolysed by a proline specific endo protease at a pH of 6.5 or lower, preferably 5.5 or lower and more preferably 5.0 or lower to hydrolyse said peptide or polypeptide.

FIELD OF THE INVENTION

The present invention relates to the proteolytic :hydrolysis of, apeptide or polypeptide.

BACKGROUND OF THE INVENTION

Proline rich dietary proteins such as caseins in bovine milk or glutensin cereals are known to resist proteolytic degradation in the humangastrointestinal tract. As a result proline rich peptides can build upand may lead to undesirable effects in specific groups of individuals.Some of these effects have been ascribed to the fact that the prolinerich peptides act as opioids that bind to receptors in peripheraltissues and the central nervous system. For example, syndromes shown byautistic and schizophrenic patients have been linked with theconsumption of proline rich dietary proteins. Other effects are theresult of an intolerance for proline rich peptides. For example specificproline rich sequences are responsible for the observed toxicity ofgluten in celiac disease. Celiac disease is a widely prevalentautoimmune disease of the small intestine which can only be treated by alife-long gluten free diet. Celiac disease is occasionally alsoaccompanied by psychiatric and neurological symptoms illustrating thefar-reaching consequences a disturbed metabolism of proline richpeptides may have.

Proteins in bovine milk are associated with growth and health and forman important ingredient in the human diet. Casein constitutesapproximately 80% of the total protein in bovine milk and is animportant source of amino acids, calcium and phosphate. Casein consistsof roughly 50% of alpha-caseins, 35% of beta-caseins, 13% ofkappa-caseins and 3% of gamma-caseins. In human milk the alpha-caseinfraction is generally absent.

It is known that upon metabolisation of casein a number of new bioactivepeptides are formed. From the alpha and beta-casein fractions opioidpeptides called alpha-casomorphins and beta-casomorphins, respectively,have been identified and isolated. The pharmacological effects ofespecially the beta-casomorphins have been extensively studied. Thebeta-casomorphin with the sequence Tyr-Pro-Phe-Pro-Gly-Pro-Ile is theprincipal opioid peptide in bovine milk and is called BCM-7(beta-casomorphin (1-7); Chang et al. (1985) Journal of BiologicalChemistry, 260, 9706-9712). Apart from this BCM-7 fragment at amino acidpositions 60-66 of the beta-casein molecule, smaller fragments of BCM-7like Tyr-Pro-Phe-Pro (beta-casomorphin (1-4)) and Tyr-Pro-Phe-Pro-Gly(beta-casomorphin (1-5)) at amino acid positions 60-63 and 60-64respectively as well as all larger BCM-7 related peptides up to a chainlength of 11 amino acids (at amino acid positions 60-70) display atleast some degree of opioid activity. The N-terminal tripeptide ofBCM-7, i.e. the sequence Tyr-Pro-Phe at position 60-62, has no opioidactivity. A genetic beta-casein variant called Al (having a histidinerather than the proline residue of A2 beta-casein at amino acid position67) is claimed to lead to the formation of increased levels of the BCM-7molecule.

The basic reason for the generation of the various beta-casomorphins isthat their amino acid sequence is relatively rich in proline residues.Because peptide bonds involving proline residues resist proteolyticbreakdown, the beta-casomorphin sequences tend to survive exposure tothe gastrointestinal proteases in the stomach and the intestinal lumen.For the same reason one may assume that these beta-casomorphin sequencestend to survive incubations with other proteases, for example thoseproteases commonly used in the industrial production of proteinhydrolysates. This assumption implies that the commonly availableprotein hydrolysates or products containing these protein hydrolysatesall contain the BCM-7 or closely related peptides. As the BCM-7 peptidefragment and its related molecules have been linked with certaindiseases, the presence of such molecules in protein hydrolysates, quiteoften used in the diet of vulnerable groups like infants, elderly andpatients, is an undesirable situation. Results of opiate receptorbinding assays of human and bovine beta-casomorphins indicate that thefragments with opioid activity bind with opiate receptors in the ratbrain membrane. It has been shown that the beta-caseins are moreselective towards mu-ligands with little affinity for delta- andkappa-receptor subtypes. According to these and other studiesbeta-casomorphins are claimed to have various gastrointestinal,analgesic, respiratory, cardiovascular, endocrine and immunomodulatoryeffects. A common structural feature of opioid peptides incorporating aproline residue is the Tyr-Pro-Phe/Trp motif (Okada et al, Vitamins andHormones 2002, 65, 257-279).

Although in normal individuals the peptidases in the intestinalepithelial layer and in the blood can cope with the beta-casomorphins,this seems not to be always the case for patients suffering fromschizophrenia, autism, ADHD or other mood disorders. For example,genetic alterations in plasma dipeptidyl peptidase IV (DPP IV) enzymeactivity leading to an incomplete breakdown of proline rich peptideshave been linked with the occurrence of these diseases. Moreoverhyperpeptiduria, i.e. an increased concentration of casein or glutenderived peptides in the urine, is regularly found (Reichelt, W. H. etal; (1997) Dev. Brain Dysfunct; 10: 44-55). Recent scientific literatureprovides compelling evidence that an incomplete degradation of prolinerich peptides may contribute to the development and the severity of suchdiseases. Apart from the caseine derived BCM-7 fragment, also glutenderived protease resistant peptides have been mentioned in thisconnection. Already in 1979 Panksepp (Trends in Neuroscience 1979;2:174-177) proposed the opioid excess theory in which he suggested thata disturbed opioid metabolism is part of the pathogenesis in autism.Nowadays we understand that many proline rich peptides are highlyresistant to cleavage by gastric and pancreatic peptidases such aspepsin, trypsin, chymotrypsin and the like and that only specificenzymes, as present in amongst others the brush border epithelial layerof the gastrointestinal tract, are capable of hydrolysing peptide bondsinvolving proline.

Gluten is the insoluble protein fraction of cereals like wheat, rye,oats, barley, maize and rice that remains after washing to remove starchand water-soluble components. Gluten can be subdivided into 4 majorsolubility fractions i.e. albumin, globulin, prolamin and glutelin.Among these especially the prolamin and the glutelin fractions of wheat,corn, barley and oats are characterized by relatively high contents ofthe amino acids proline and glutamine. Recent evidence has implicatedthe proline rich gluten sequences as a major factor in the developmentof celiac disease. Celiac disease, also known as celiac sprue, is anautoimmunedisease of the small intestine caused by the ingestion ofgluten proteins. It commonly appears in early childhood with severesymptoms like chronic diarrhea and abdominal distension; later in lifesymptoms include fatigue, weight loss due to malabsorption andneurological symptoms. Among the proline rich fractions of the variouscereals, alpha-gliadin from wheat, hordein from barley, secalin from ryeand avenin from oats seem to be most toxic (Schuppan, D.;Gastroenterology 2000; 119:234-242). A life-long gluten free diet is theonly effective treatment for celiac disease patients. Among celiacpatients a high prevalence of various autoimmune disorders, especiallytype 1 diabetes, dermatitis herpetiformis, autoimmune thyroiditis,collagen diseases, autoimmune alopecia and autoimmune hepatitis has beenobserved. This indicates that by unknown mechanisms untreated celiacdisease predisposes to autoimmunity to other organs (Schuppan, D. 2000Gasteroenterology 119:234-242). Furthermore there are indications that amild form of celiac disease is present in a group of people sufferingfrom irritable bowel syndrome (IBS). IBS is a disorder that interfereswith the normal functions of the large intestine and is characterized bycrampy abdominal pain, constipation and diarrhea. IBS usually beginsaround the age of 20 and causes a great deal of discomfort and distress.The eating of wheat, barley, rye or milk products has been associatedwith a worsening of IBS symptoms.

Recently Shan et al (Science; vol 297, 27 Sep. 2002: 2275-2279)identified a gliadin-derived, proline rich, 33 amino acids long peptidethought to be the source of a set of major celiac patient-specific Tcell epitopes. Whereas an enzyme extract prepared from small intestinebrush-border cells was unable to hydrolyse this 33-mer, suppletion witha bacterial prolyl oligopeptidase from Flavobacterium meningosepticumled to a rapid digestion with a concomitant strongly decreasedstimulation of a, relevant T cell clone. In imitation of earlier work onthe oral administration of papain (Messer, M. and Baume, P. E.; Lancet1976; 2:1022), the article indicates the potential of the prolyloligopeptidase as a dietary enzyme in detoxifying gluten by enzymetherapy.

Prolyl oligopeptidases (EC 3.4.21.26) have the unique possibility ofpreferentially cleaving peptides at the carboxyl side of prolineresidues. In the prolyl oligopeptidases isolated from mammalian sourcesas well as in the prolyl oligopeptidase isolated from Flavobacteriummeningosepticum a unique peptidase domain has been identified thatexcludes large structured proteins from the enzyme's active site. Infact these enzymes are unable to degrade proteins containing more thanabout 30 amino acid residues so that these enzymes are now referred toas “prolyl oligopeptidases” (Fulop et al: Cell, Vol. 94, 161-170, Jul.24, 1998). All known prolyl oligopeptidases are cytosolic enzymes thatexhibit pH optima near neutrality and are characterized by the fact thatthey cannot efficiently degrade molecules containing more thanapproximately 30 amino acid residues. The fact that these enzymesexhibit pH optima that correspond with the pH values prevailing in themore distal part of the gastrointestinal tract, makes them ideallysuitable as dietary supplements supporting the intestinal digestionprocess of dietary gluten.

Another enzyme that can have a benefit in the inactivation of toxicproline rich peptides, is the enzyme dipeptidyl peptidase IV(US2002/0041871A). Dipeptidylpeptidase IV, also calledXaa-Pro-dipeptidyl-aminopeptidase (EC 3.4.14.5) catalyzes the release ofan N-terminal dipeptide, Xaa-Xbb from a peptide with the N-terminalsequence Xaa-Xbb-Xcc-, preferentially when Xbb is proline and providedXcc is not proline. Dipeptidyl-peptidase IV has been isolated from alarge number of mammalian sources, for example the intestinal brushborder membranes form a rich source of the enzyme. Furthermore theenzyme has been isolated from microbial sources such as the food grademicroorganisms Saccharomyces, Lactococcus and Aspergillus. Like theprolyl oligopeptidases, all known dipeptidyl-peptidases IV are enzymeswith near neutral pH optima and thus suited for supporting theintestinal digestion process.

Because of the possible implications of the proline specificoligopeptidase and the dipeptidyl-peptidase IV in the treatment ofceliac disease or schizophrenia, autism or other mood disorders, thesedata have resulted in a number of patent applications that deal withvarious aspects of this matter. For example U.S. Pat. No. 6,447,772 andWO 01/24816 describe compositions containing dipeptidyl peptidase IV, WO03/068170 describes compositions containing proline specificoligopeptidases optionally combined with dipeptidyl-peptidase IV, WO02/45523 describes low allergenic protein hydrolysates prepared withproline specific endoproteases and WO 03/028745 describes compositionscomprising bacterial strains that can lower the concentration ofintestinal toxic proline rich peptides. WO 96/36239 describes theadvantages of products derived from cattle substantially free of thebeta-casein A1 allele.

SUMMARY OF THE INVENTION

The present invention relates to a process for the proteolytichydrolysis of a peptide or a polypeptide, said peptide or polypeptidecomprising 4 to 40, preferably 5 to 35, amino acid residues and saidpeptide or polypeptide is not hydrolysable by subtilisin whereby saidpeptide or polypeptide is hydrolysed by a proline specific endo proteaseat a pH of 6.5 or lower, preferably 5.5 or lower and more preferably 5.0or lower to hydrolyse said peptide or polypeptide. Preferably at least70%, more preferably at least 80%, and most preferably at least 90% ofthe peptide or polypeptide is hydrolysed in this process.

According to another embodiment the process of the invention relates toa process for the proteolytic hydrolysis of a peptide or a polypeptide,said peptide or polypeptide comprising 4 to 40, preferably 5 to 35,amino acid residues and comprises the tripeptide motif Glu-Xxx-Pro,Gln-Xxx-Pro , Tyr-Pro-Phe or Tyr-Pro-Trp whereby said peptide orpolypeptide is hydrolysed by a proline specific endo protease at a pH of6.5 or lower, preferably 5.5 or lower and more preferably 5.0 or lowerto hydrolyse said peptide or polypeptide. Preferably at least 70%, morepreferably at least 80%, and most preferably at least 90% of the peptideor polypeptide is hydrolysed in this process.

Moreover the present invention provides a process for the proteolytichydrolysis of a peptide or a polypeptide, said peptide or polypeptidecomprising 4 to 40, preferably 5 to 35 amino acid residues, and wherebythe amino acid residues of the peptide or polypeptide comprises for atleast 30%, preferably at least 40%, proline and/or glutamine residueswhereby said peptide or polypeptide is hydrolysed by a proline specificendo protease at a pH of 6.5 or lower, preferably 5.5 or lower and morepreferably 5.0 or lower to hydrolyse said peptide or polypeptide withthe proviso that the peptide or polypeptide comprises at least 10% ofproline residues. Preferably at least 70%, more preferably at least 80%,and most preferably at least 90% of the peptide or polypeptide ishydrolysed in this process.

Preferably the peptide or polypeptide in the process of the inventioncomprises the motif Gln-Xxx-Pro or Glu-Xxx-Pro and contains 9 or moreamino acid residues. This peptide or polypeptide is advantageouslyhydrolysed into a peptide containing 8 or less amino acid residues. Incase the peptide or polypeptide has the motif Tyr-Pro-Phe orTyr-Pro-Trp, preferably the bond between Pro and Phe or Pro and Trp ishydrolysed.

The preferred endoproline specific endo protease used in the process ofthe invention is preferably a proline specific endo protease derivedfrom Aspergillus or belonging to the S28 family of serine proteases.This enzyme has preferably a pH optimum below 6.5, preferably below 5.5,more preferably below 5.0 to hydrolyse a peptide or polypeptidecomprising 4 to 40, preferably 5 to 35, amino acid residues that is nothydrolysable by subtilisin.

The proline specific endoprotease can be used to hydrolyse at pH ofbelow 5.5, proline rich peptides which are brought in relation withpsychiatric disorders including autism, schizophrenia, ADHD, bipolarmood disorder and depression and celiac disease linked disorders likeautoimmune disorders, especially type 1 diabetes, dermatitisherpetiformis, autoimmune thyroiditis, collagen diseases, autoimmunealopecia and autoimmune hepatitis and IBS.

Advantageously this enzyme is used to produce food, for example beer orbread which is devoid of celiac related epitopes, preferably glutenepitopes, more preferably wheat or barley epitopes.

The present invention also relates to proline specific endoprotease foruse as a medicament or for the use in manufacturing a medicament, whichpreferably is an Aspergillus, more preferably an Aspergillus nigerenzyme.

According to another embodiment of the invention a proline specificendoprotease is used for the manufacture of a dietary supplement or amedicament for treatment or prevention of psychiatric disordersincluding autism, schizophrenia, ADHD, bipolar mood disorder anddepression and celiac disease linked disorders like autoimmne disorders,especially type 1 diabetes, dermatitis herpetiformis, autoimmunethyroiditis, collagen diseases, autoimmune alopecia and autoimmunehepatitis and IBS

Advantageously a proline specific endoprotease is used for themanufacture of a dietary supplement or a medicament for individualsbelow the age of 25 years.

According to the present invention a proline specific endoprotease isalso used for a dietary supplement or a medicament for treatment orpreventing of psychiatric disorders including autism, schizophrenia,ADHD, bipolar mood disorder and depression and celiac disease linkeddisorders like autoimmne disorders, especially type 1 diabetes,dermatitis herpetiformis, autoimmune thyroiditis, collagen diseases,autoimmune alopecia and autoimmune hepatitis and IBS.

Furthermore the present invention relates to the use of proline specificendoprotease to hydrolyse protein or peptides having more than 30 aminoacid residues. In the uses according to the invention, preferablyAspergillus, more preferably A. niger proline specific endoprotease isapplied.

The present invention also relates to the use of a praline-specificprotease that is active at a pH of 5 or below 5 in the presence ofpepsin.

Advantageously the present invention relates to a process for theproteolytic hydrolysis of said peptides or protein present in milkproteins obtained from cattle carrying the beta-casein A1 or thebeta-casein A2 allele.

Protein can also be used in the process of the invention. First theprotein has to be hydrolysed into peptides comprising 4 to 40 amino acidresidues. The hydrolysis of protein can be done prior to or simultaneouswith the process of the present invention.

Furthermore the present invention relates to the use of a prolinespecific endoprotease having a pH optimum below 6.5, preferably below5.5, more preferably below 5.0 as a dietary supplement, as a medicament,for the production of a dietary supplement, for the production ofmedicament or for the production of feed including pet food, intendedfor a non-human animal, preferably a mammal.

DETAILED DESCRIPTION OF THE INVENTION

In general the prior art aims at either the removal of toxic prolinerich peptides from food prior to consumption or at the oral supply ofcorrective enzymes to compensate for an inadequate intestinal digestionprocess. In a normal gastrointestinal digestion process, proteolysis inthe stomach by the enzyme pepsin is understood to be the first step inthe breakdown of dietary proteins. The second step takes place in thesmall intestine, i.e. the duodenum and the jejunum located immediatelydownstream of the stomach. In the duodenum the acid pH of the stomachcontents is raised by the addition of pancreatic juices also containinga variety of endo- and carboxypeptidases. Catalysed by the latterenzymes a further breakdown of pepsin degraded dietary protein isaccomplished in the lumen of duodenum and jejunum at pH values above 5.Prior to transport over the intestinal wall, a third step involves afurther peptide hydrolysis in the brush border surface membrane of theintestestinal epithelium. The latter step is accomplished by a number ofproteases including DPP IV that are localized in the membranes of theseepithelial cells. The prior art suggests that in the intestine ofindividuals suffering from some of the diseases the present invention isaiming at, some of these epithelial enzymes and notably DPP IV is partlyinactive or not even present. In celiac patients the levels of theseepithelial enzymes are probably normal but within this group ofindividuals even low levels of certain proline rich peptides can elicitan strong inflammatory T-cell response. The solution presented in priorart is that orally corrective enzymes are introduced into the human gutin order to minimise the levels of toxic proline rich peptides presentin the lumen of the gut. In this approach the prior art has selectedenzymes that imitate the natural human enzymes as much as possible i.e.the enzymes are active in the gut under conditions above pH 5. Theseprior art enzymes are not active under acidic conditions or the oralpresentation forms containing these prior art enzymes are adequatelycoated to prevent their activity under acid conditions.

The present inventors have found that an enzyme deploying its mainactivity under acid conditions in the stomach offers a superior solutionfor the problem of insufficiently digested proline rich peptides. Thisapproach is new and opens the possibility of using other enzymes thanthe ones mentioned in the literature for solving the problem.

As discussed above several publications point towards the possibilitiesof using enzymes like dipeptidyl peptidase IV and prolyl oligopeptidasein preventing a disturbed opioid metabolism. Thereto dipeptidylpeptidase IV as well as the prolyl oligopeptidase enzymes are selectedthat typically are active under near neutral pH conditions. Theimplication is that these enzymes will only efficiently hydrolyseproline rich proteins under conditions above pH 5. Taking the pH profileof the human gastrointestinal tract into consideration, these prior artenzymes will not become active before reaching the distal part of theduodenum, i.e. well beyond the stomach. However, the distal part of theduodenum is a major site for protein absorption and is also known to beaffected in celiac disease patients. So in fact these prior art enzymeswill start to work where part of the damage is done.

Furthermore the prior art enzymes become active only after a significantpre-degradation of proline rich proteins. The time required to achievethis pre-degradation by pancreatic enzymes further limits the periodavailable for the orally applied enzymes to achieve a completehydrolysis of proline rich sequences. According to the present inventionan enzyme is used that can degrade most of the proline rich and/orglutamine rich protein sequences before the food enters the smallintestine. The normal food residence time in the stomach provides thetime period required for an adequate hydrolysis of proline rich orglutamine rich proteins. Furthermore according to the present inventionpreferably an enzyme is used that is able to cleave peptides at thecarboxyl side of proline residues and is also able to cleave intactproteins at the carboxyl side of proline residues and even in thepresence of pepsin. Prior art enzymes will be hydrolysed under the lowpH conditions of the stomach and if exposed to the proteolytic pepsinenzyme that is secreted into the stomach. However up to now the use ofsuch an acid/pepsin stable enzyme is not known in the present process.The present approach will result in the substantial breakdown of prolinerich peptides, polypeptides and proteins before the intestine is reachedinstead of the prior art approach which suggests to mimic the naturalprocess of hydrolysing proline rich peptides in the intestine. Thepreferred enzyme used in the process of the invention is an enzyme thatis active at pH values below 5 in the presence of pepsin and is capableto break down dietary proteins or polypeptides as well as peptides. Theprior art solutions always need a co-enzyme that prehydrolyses thedietary protein into peptides and only thereafter the additional prolinespecific enzymes can start to deploy their activity.

A “peptide” or “oligopeptide” is defined herein as a chain of two tothirty amino acid residues that are linked through peptide bonds. Theterms “peptide” and “oligopeptide” are considered synonymous (as iscommonly recognized) and each term can be used interchangeably as thecontext requires. A “polypeptide” is defined herein as a chaincontaining more than 30 amino acid residues.

Peptides or polypeptides having four to forty amino acid residues thatare not hydrolysable by subtilisin (EC 3.4.21.62), preferably subtilisinCarlsberg are understood to be peptides or polypeptides that after anincubation of 2 hours at pH 8.0 and 60 degrees C. in a suspension orsolution containing 20 g/l protein and an enzyme to substrate ratio of0.12 AU-A (Anson Units Alcalase) Protease Units per gram proteinremain-intact. The AU-A Protease Unit is defined as specified in theAnalytical Method LUNA #2003-32153-01 as issued by Novozymes (Denmark).Intact meaning that after the incubation the original peptide orpolypeptide forms more than 80%, preferably more than 90%, morepreferably more than 95% of the resulting enzyme reaction products. Inpractice the enzyme digestion is carried out under the conditionsindicated and using 40 microliter of Alcalase per gram of substrateprotein present. Examples of such a non-hydrolysable peptide is theVYPFPGPIPN peptide resulting from the beta-casein hydrolysis describedin Example 4. Another example of such a non-hydrolysable polypeptide isthe 33-mer described in Example 6.

An oligopeptidase is an enzyme classified as EC 3.4.21.26 and belongingto the family of serine proteases clan SC, family S9.

All (oligo)peptide and polypeptide formulas or sequences herein arewritten from left to right in the direction from amino-terminus tocarboxy-terminus, in accordance with common practice. The one-lettercode of amino acids used herein is commonly known in the art and can befound in Sambrook, et al. (Molecular Cloning: A Laboratory Manual, 2nd,ed. Cold Spring Harbor Laboratory, Cold Spring Harbor Laboratory Press,Cold Spring Harbor, N.Y., 1989). The amino acid Xxx, Xaa, Xbb or Xcc ismeant to be any amino acid. By a motif is meant an amino acid sequence,which is part of a peptide, polypeptide or protein. Herein glutamine (Qor Gln) is understood be glutamine or glutamate (E or Glu). For example,in chemical deamidated gluten a large part of natural glutamine residuespresent is converted into glutamate. So the motif Gln-Xxx-Pro is alsocomprising the motif Glu-Xxx-Pro. Also in other peptide, polypeptide orprotein glumine can be converted into glutamate, for example due to pHconditions, temperature or by enzymatic conversion for example by transglutaminase.

By a proline rich peptide or polypeptide is meant a peptide orpolypeptide comprising 4 to 40 amino acid residues whereby the aminoacid residues of the peptide or polypeptide comprises for at least 30%,preferably at least 40% of proline and/or glutamine residues with theproviso that the peptide or polypeptide comprises at least 10% ofproline residues. A dietary supplement is according to the adapteddefinition of the DSHEA, a product (other than tobacco) that is intendedto supplement the diet that bears or contains one or more of thefollowing dietary ingredients: a protein including an enzyme, apolypeptide, a peptide, a vitamin, a mineral, an herb or, otherbotanical, an amino acid, a dietary substance for use by man tosupplement the diet by increasing the total intake, or a concentrate,metabolite, constituent, extract, or combinations of these ingredients.Moreover a dietary supplement

-   is intended for ingestion in pill, capsule, tablet, or liquid form.-   is not represented for use as a conventional food or as the sole    item of a meal or diet.-   is, in general, labelled as a “dietary supplement”.-   includes products such as an approved new drug, certified    antibiotic, or licensed biologic that was marketed as a dietary    supplement of food before approval, certification, or license    (unless the Secretary of Health and Human Services waives this    provision).

Toxic proline rich peptides or polypeptides are peptides or polypeptidesimplicated in the binding to opioid receptors or in the development orthe severity of psychiatric or celiac disorders.

Psychiatric disorders include autism, schizophrenia, ADHD, bipolar mooddisorder as well as depression.

Celiac disease linked disorders are autoimmune disorders, especiallytype 1 diabetes, dermatitis herpetiformis, autoimmune thyroiditis,collagen diseases, autoimmune alopecia and autoimmune hepatitis.

The internationally recognized schemes for the classification andnomenclature of all enzymes from IUMB include proteases. The updatedIUMB text for protease EC numbers can be found at the Internet site:

http://www.chem.qmw/ac.uk/iubmb/enzyme/EC3/4/11/. In this system enzymesare defined by the fact that they catalyse a single reaction. The systemcategorises the proteases into endo- and exoproteases. Endoproteases arethose enzymes that hydrolyse internal peptide bonds, exoproteaseshydrolyse peptide bonds adjacent to a terminal α-amino group(“aminopeptidases”), or a peptide bond between the terminal carboxylgroup and the penultimate amino acid (“carboxypeptidases”). Theendoproteases are divided into sub-subclasses on the basis of catalyticmechanism. There are sub-subclasses of serine endoproteases (EC 3.4.21),cysteine endoproteases (EC 3.4.22), aspartic endoproteases (EC 3.4.23),metalloendoproteases (EC 3.4.24) and threonine endoproteases (EC3.4.25).

WO 02/45524 describes a proline specific endoprotease obtainable fromAspergillus niger. Surprisingly we have found now that this Aspergillusenzyme is advantageously used in the present process under the acidconditions in the stomach and can hydrolyse intact dietary proteins,polypeptides as well as smaller peptide molecules under these conditionsas well. Furthermore this enzyme survives the presence of the enzymepepsin under acid conditions and is likely to continue its activitythroughout the duodenum. We demonstrate that the A. niger derivedproline specific endoprotease is quite different from the known prolinespecific proteases as well as the glutenases specified in WO 03/068170,from an activity as well as from an evolutionary point of view. Thelatter feature is amply demonstrated by the fact that the amino acidsequence homologies between the glutenases specified in WO 03/068170 andthe A. niger derived enzyme are typically below 20% using a globalalignment algorithm analysis. This result is in accordance with thecurrent view that prolyl oligopeptidases do not occur in fungi such asAspergillus niger from which the proline specific endoprotease accordingto the present invention is isolated (Venäläinen, J. I. et al, Eur JBiochem 271, 2705-2715 (2004)).

By the proline specific endo protease according to the invention or usedaccording to the invention is meant for example the polypeptide asmentioned in claims 1-5, 11 and 13 of WO 02/45524 which is incorporatedhere by reference. Therefore this proline specific endo protease is apolypeptide which has proline specific endoproteolytic activity,selected from the group consisting of:

(a) a polypeptide which has an amino acid sequence which has at least40% amino acid sequence identity with amino acids 1 to 526 of SEQ IDNO:2 or a fragment thereof;

(b) a polypeptide which is encoded by a polynucleotide which hybridizesunder low stringency conditions with (i) the nucleic acid sequence ofSEQ ID NO:1 or a fragment thereof which is at least 80% or 90% identicalover 60, preferably over 100 nucleotides, more preferably at least 90%identical over 200 nucleotides, or (ii) a nucleic acid sequencecomplementary to the nucleic acid sequence of SEQ ID NO:1. The SEQ IDNO:1 and SEQ ID NO:2 as shown in WO 02/45524. Preferably the polypeptideis in isolated form.

The preferred polypeptide has an amino acid sequence which has at least50%, preferably at least 60%, preferably at least 65%, preferably atleast 70%, more preferably at least 80%, even more preferably at least90%, most preferably at least 95%, and even most preferably at leastabout 97% identity with amino acids 1 to 526 of SEQ ID NO: 2 orcomprising the amino acid sequence of SEQ ID NO:2.

Preferably the polypeptide is encoded by a polynucleotide thathybridizes under low stringency conditions, more preferably mediumstringency conditions, and most preferably high stringency conditions,with (i) the nucleic acid sequence of SEQ ID NO:1 or a fragment thereof,or (ii) a nucleic acid sequence complementary to the nucleic acidsequence of SEQ ID NO: 1.

The term “capable of hybridizing” means that the target polynucleotideof the invention can hybridize to the nucleic acid used as a probe (forexample, the nucleotide sequence set forth in SEQ. ID NO: 1, or afragment thereof, or the complement of SEQ ID NO: 1) at a levelsignificantly above background. The invention also includes thepolynucleotides that encode the proline specific endoprotease of theinvention, as well as nucleotide sequences which are complementarythereto. The nucleotide sequence may be RNA or DNA, including genomicDNA, synthetic DNA or cDNA. Preferably, the nucleotide sequence is DNAand most preferably, a genomic DNA sequence. Typically, a polynucleotideof the invention comprises a contiguous sequence of nucleotides which iscapable of hybridizing under selective conditions to the coding sequenceor the complement of the coding sequence of SEQ ID NO: 1. Suchnucleotides can be synthesized according to methods well known in theart.

A polynucleotide of the invention can hybridize to the coding sequenceor the complement of the coding sequence of SEQ ID NO:1 at a levelsignificantly above background. Background hybridization may occur, forexample, because of other cDNAs present in a cDNA library. The signallevel generated by the interaction between a polynucleotide of theinvention and the coding sequence or complement of the coding sequenceof SEQ ID NO: 1 is typically at least 10 fold, preferably at least 20fold, more preferably at least 50 fold, and even more preferably atleast 100 fold, as intense as interactions between other polynucleotidesand the coding sequence of SEQ ID NO: 1. The intensity of interactionmay be measured, for example, by radiolabelling the probe, for examplewith ³²P. Selective hybridization may typically be achieved usingconditions of low stringency (0.3M sodium chloride and 0.03M sodiumcitrate at about 40° C.), medium stringency (for example, 0.3M sodiumchloride and 0.03M sodium citrate at about 50° C.) or high stringency(for example, 0.3M sodium chloride and 0.03M sodium citrate at about 60°C.).

The UWGCG Package provides the BESTFIT program which may be used tocalculate identity (for example used on its default settings).

The PILEUP and BLAST N algorithms can also be used to calculate sequenceidentity or to line up sequences (such as identifying equivalent orcorresponding sequences, for example on their default settings).

Software for performing BLAST analyses is publicly available through theNational Center for Biotechnology Information(http://www.ncbi.nlm.nih.qov/). This algorithm involves firstidentifying high scoring sequence pair (HSPs) by identifying short wordsof length W in the query sequence that either match or satisfy somepositive-valued threshold score T when aligned with a word of the samelength in a database sequence. T is referred to as the neighborhood wordscore threshold. These initial neighbourhood word hits act as seeds forinitiating searches to find HSPs containing them. The word hits areextended in both directions along each sequence for as far as thecumulative alignment score can be increased. Extensions for the wordhits in each direction are halted when: the cumulative alignment scorefalls off by the quantity X from its maximum achieved value; thecumulative score goes to zero or below, due to the accumulation of oneor more negative-scoring residue alignments; or the end of eithersequence is reached. The BLAST algorithm parameters W, T and X determinethe sensitivity and speed of the alignment. The BLAST program uses asdefaults a word length (W) of 11, the BLOSUM62 scoring matrix alignments(B) of 50, expectation (E) of 10, M=5, N=4, and a comparison of bothstrands.

The BLAST algorithm performs a statistical analysis of the similaritybetween two sequences. One measure of similarity provided by the BLASTalgorithm is the smallest sum probability (P(N)), which provides anindication of the probability by which a match between two nucleotide oramino acid sequences would occur by chance. For example, a sequence isconsidered similar to another sequence if the smallest sum probabilityin comparison of the first sequence to the second sequence is less thanabout 1, preferably less than about 0.1, more preferably less than about0.01, and most preferably less than about 0.001.

The enzyme according to the invention is preferably obtained from afungus, preferably an Aspergillus, more preferably from Aspergillusniger. So, the Aspergillus derived enzyme is found to be a trueendoprotease that is acid stable and preferably not affected by thepresence of pepsin under pH conditions that prevail in the stomach.Proline specific oligopeptidases in general including the enzyme as canbe obtained from Flavobacterium meningosepticum have almost no activityat and below pH 5 and are inactivated by the combination of a low pH andthe presence of the enzyme pepsin. Furthermore proline specificproteases in general are unable to degrade intact proteins and werefound to efficiently hydrolyse smaller peptides only, i.e. peptides upto a length of approximately 30 amino acid residues.

The present invention provides economical, food grade compositions todefer or to minimise the phenomena of toxic proline rich peptides or ofa disturbed opioid metabolism. The compositions include oral enzymeformulations suited for alimentary, pharmaceutical and veterinary use aswell as enzyme formulations suited for the production of proteinhydrolysates and food products with significantly lowered levels ofopioid or toxic proline rich peptides.

The present invention discloses methods to hydrolyse proline richpeptides or polypeptides which are brought in relation with thedevelopment of psychiatric disorders or celiac disease or of a disturbedopioid metabolism. The present invention also discloses methods toproduce foods that can prevent or delay the development of suchdisorders in infants or in general for individuals below the age of 25years. Also foods that are better tolerated by people suffering fromceliac disease and abdominal symptoms associated with IBS can beprepared by such methods. An embodiment of the present invention isrelated to the breakdown of these proline rich peptides or polypeptidesbefore consumption hereby preventing or minimising exposure of the bodyto toxic proline rich peptides. In infants this will avoid an earlyexposure to opioids and the immature immune system will not besensitised by such toxic proline rich peptides. Also for teenagers andadults a diet containing reduced levels of toxic proline rich peptideswill have prophylactic benefits, e.g. for people suffering from anunnoticed celiac disease or from IBS. The invention also relates to thesuppletion of a suitable enzyme for the breakdown in the body (human oranimal) of these toxic proline rich peptides or peptides in the stomach,i.e. under acid pH conditions, preferably under, conditions below pH 5.According to the latter embodiment persons suffering from celiacdisease, diseases associated with the occurrence of celiac disease ordiseases caused by a decreased level of body proline specific proteasesrequired for the breakdown of these peptides or polypeptides, arecapable to degrade the relevant proline rich peptides or polypeptides inthe stomach and in the proximal part of the duodenum. Moreover theenzymes according to the present invention do not require protectivecoatings.

Preferably at least 80% of the toxic proline rich peptides orpolypeptides which are formed upon an incubation of peptides orpolypeptides or protein with subtilisin (EC 3.4.21.62) preferably aBacillus licheniformis subtilisin (or subtilisin Carlsberg) underneutral pH conditions are hydrolysed by the proline specificendoprotease according to the invention. The formation of suchsubtilisin resistant peptides is illustrated in Example 4 of thisapplication. Such subtilisin resistant proline rich peptides are oftenrelated with the diseases mentioned above. Examples of these peptidesare BCM-7, BCM-7 related peptides i.e. peptides comprising the aminoacid sequence YPFP as present at position 60 to 63 of the beta-caseinmolecule. Furthermore gliadin derived peptides comprising the motifGln-Xxx-Pro (Q-X-P), for example the PYPQPQLPY epitope, as well as othersubtilisin resistant molecules comprising this Q-X-P or E-X-P motif thatcan be obtained from gliadin, hordein, secalin or avenin are exampleshereof. More preferably at least 90%, still more preferably at least 95%and most preferably at least 99% of proline rich peptides which would beformed by hydrolysis by subtilisin are broken down or are not formed byusing the proline specific endoprotease according to the invention. Mostpreferably these proline rich peptides can be degraded according to theprocess of the invention under conditions below pH 5.5.

One way of supplying the required enzymes would be in the form of adigestive aid, e.g. as stabilized enzyme formulations that arecoingested with the food to help the gastro-intestinal digestion ofdietary proline rich peptides or polypeptides. Another way would be toprevent or to limit the ingestion of the problematic toxic proline richsequences, e.g. by using protein food “pre-digested” with Aspergillusenzyme. Such protein food could be supplied in the form of ahydrolysate, e.g. a gluten or a milk protein hydrolysate and includeshydrolysates that have been extensively digested by endo- as well asexoproteases to release large quantities of free amino acids A typicalexample of the latter application would be the generation of glutenhydrolysates rich in glutamate for a.o. savoury applications. Thehydrolysate could be consumed as such or could serve as a foodingredient. In another way the invention provides the use of acomposition for improving the tolerability of food productscharacterized in that the composition comprises an acid stableproline-specific endoprotease according to the invention. In yet anotherway the invention provides a process for preparing a food comprising theaddition of an acid stable proline-specific endoprotease for an improvedtolerability of a food product. In all such applications the prolinespecific enzyme would be used as a so-called processing aid.

The strains of the genus Aspergillus have a food grade status andenzymes derived from these micro-organisms are known to be from anunsuspect food grade source. According to another preferred embodiment,the enzyme is secreted by its producing cell rather than representing anon-secreted, so called cytosolic or periplasmatic enzyme. In this wayenzymes can be recovered from the cell broth in an essentially purestate without expensive purification steps. Preferably the enzyme has ahigh affinity towards its substrate under the prevailing pH andtemperature conditions. Preferably the enzyme is not inactivated by thegastrointestinal proteolytic enzymes such as pepsin or trypsin, elastaseand chymotrypsin under the pH conditions of that relevant part of thegastrointestinal tract. More preferably the enzyme is active in thestomach as well as in the duodenum and does not require a protectivecoating.

The alimentary canal of humans is a sequence of different compartments.Food is ingested and after swallowing, it reaches the stomach where itis mixed with acid and the endoprotease pepsin. Typical residence timesof solid food in the stomach range from one to a few hours. Occasionalopening of the pyloris allows the acidified and partly hydrolysed foodto flow into the small intestine. In the first part of the smallintestine i.e. in the duodenum, bile as well as pancreatic juice areadded. The pancreatic juice contains bicarbonate to partly neutralizethe stomach contents. The pancreatic juice also contains an additionalset of proteases, i.e. the endoproteases trypsin, chymotrypsin andelastase as well as the carboxypeptidases A and B to further degrade thepeptides and polypeptides formed by the pepsin in the stomach. After theduodenum, the digest reaches the jejunum. The duodenum and the jejunumare the major sites for protein absorption in the gastrointestinaltract. This absorbtion process involves a further proteolytic breakdownof the dietary proteins by different proteases anchored in the brushborder cells of the intestinal epithelium. The latter hydrolysis isaccompanied by a facilitated transport of small peptides as well as freeamino acids over the intestinal wall. The last part of the smallintestine is formed by the ileum, after which the digest enters thelarge intestine (colon).ln the colon, there is an intensive fermentationbut there is no appreciable absorption of amino acids or peptides.

Ingestion of gluten by celiac disease patients leads to lesions of theproximal small intestine. Atrophy of the intestinal villi is one mostcharacteristic features of such lesions. This villous atrophy is notrestricted to the jejunum but can also be demonstrated in the distalduodenum (Meijer, J. W. R. et al; Virchows Arch. 2003 February;442:124-128). This observation indicates that in celiac patients thedamaging effects of toxic proline rich peptides is already apparent inan area immediately downstream of the stomach. We have found that enzymetherapies aiming at the prevention of the symptoms of celiac diseaseshould be aimed at hydrolyzing the relevant proline rich peptides in thestomach rather than in the more distal part of the gastrointestinaltract. Advantageously the activity of the enzyme applied in the enzymetherapy is such that it starts to work in the stomach and continues tobe active in the duodenum. We have found that also opioid peptidesplaying a role in the development of psychiatric, respiratory andcardiovascular disorders are best destroyed in the stomach. As theduodenum and the jejunum are the major sites for protein absorption, thelevel of toxic peptides in this part of the small intestine should be aslow as possible to minimise the symptoms associated with the presence ofthese toxic peptides.

In the use as digestive aid, the corrective enzyme should besufficiently active at a temperature of 37 degrees C. and shouldpreferably have a low pH optimum to survive the acid conditions in thestomach. According to published data the acidity of ingested fooddecreases from an initial pH 5 value to pH 3.5 thirty minutes afteringestion followed by a further decrease to pH 2 sixty minutes afteringestion (thesis Mans Minkus; University of Utrecht, The Netherlands;ISBN:90-393-1666-X). So ideally enzymes intended for enzyme therapyshould be active under pH values as low as 2. Studies on gastricemptying indicate that 45 minutes after intake almost 90% of the solidfood is still present in the stomach (R. Notivol et al., 1984. Scand J.Gastroenterol.19: 1107-1113). Beyond the stomach, the pH of the foodslowly rises to reach a pH of 5 in the distal part of the duodenum, i.e.approx 50 cm beyond the pyloris (Handbook of Physiology, AmericanPhysiological Society, Washington, D.C.,1968, Ed. Werner Heidel; Section6: Alimentary Canal, Volume 111, pp 1457-1490). In WO 03/068170different “glutenases” are specified that can decrease the levels oftoxic gluten oligopeptides in foodstuffs, either prior to or afteringestion by a patient. The term “glutenase” refers to protease orpeptidase enzymes, more specifically prolyl-specific proteases, that arecapable of cleaving toxic oligopeptides of gluten proteins intonon-toxic fragments. As all of these glutanases mentioned typically areintended to be active in the intestine, they are optimally active undernear neutral pH conditions. WO 03/068170 teaches the degradation oftoxic proline rich peptides in or beyond the duodenum rather than in thestomach or the proximal part of the duodenum. Moreover WO 03/068170aimes at enzyme preparations protected by so called enteric coatingswhich mask the enzyme activity at low pH so that the enzymes presentwill pass through the stomach and only become active in the intestineunder neutral pH conditions.

If used as industrial processing aid in the production of proteinhydrolysates, the enzyme should be sufficiently active under conditionsthat allow microbially safe incubations under non-sterile industrialconditions. Adequate enzyme activity at a processing temperature of atleast 50 degrees C. and a pH value well below pH 5.5 meets theserequirements.

The basidiomycete Agaricus bisporus (Sattar et al; J. Biochem. 107,256-261 (1990)) and the non-related ascomycete Aspergillus niger (WO02/45524) have both been shown to produce an extracellular prolylendopeptidase. However, the enzyme obtained from the basidiomycete willnot survive pH values below 5 and is therefore less attractive.Preferably a prolyl endopeptidase from A. niger is used which has anacid pH optimum.

The present invention provides enzyme preparations which combine lowcosts, legislative acceptance with a proven efficacy under acid pHconditions towards proline rich peptide sequences. Preferably the sameenzyme can be used to degrade not only the A1 as well as the A2-typebeta-casomorphins but also various gluten epitopes.

This Aspergillus derived proline specific endoprotease is found to bevery active in breaking down proline rich peptides or polypeptides oreven proteins. Advantageously this enzyme is secreted by the producingmicroorganism into the fermentation broth, has an acid pH optimum andcan be produced food grade and in an economic way. The relevantbeta-casomorphin peptides contain up to four proline residues in themolecule and, moreover, the A1 and the A2 beta-casomorphins havedifferent amino acid sequences. Quite surprisingly we have found thatthe Aspergillus enzyme is capable of hydrolysing beta-casomorphins atthe C-terminal side of the proline at position 61 and thus effectivelyinactivates all BCM-7 and BCM-7 related peptides, both for A1 or A2beta-casein. This is quite remarkable because we have found that awidely used and highly aggressive endoprotease with a broad substratespecificity such as subtilisin (EC 3.4.21.64) commercially available asfor example Alcalase, is not able to degrade BCM-7. Similarly otherindustrially available proteases will not be able to degrade BCM-7. Infact the Aspergillus derived proline specific endoprotease can hydrolysebeta-casomophine but, quite surprisingly, at only one of the fourproline residues present in BCM-7. Nevertheless, because of thespecificity of this particular Aspergillus enzyme towards thisparticular proline residue, BCM-7 as well as all BCM-7 related moleculesare effectively destroyed by incubation with this enzyme because theTyr-Pro-Phe motif is cleaved by the enzyme. Moreover, BCM-7 moleculesderived from A1 as well as from A2 beta-caseins are inactivated byincubation with the Aspergillus proline specific endoprotease.

The advantage of a true proline specific end oprotease is that theproline specific endoprotease can start hydrolysing proline richsequences immediately upon contacting the enzyme with the protein.Prolyl oligopeptidases can become active only after a significantpre-degradation of the gluten or casein molecules by other, for examplegastrointestinal endoproteases. In view of the required extensivedegradation and the limited time available before the food enters thesmall intestine, a true praline specific endoprotease has significantapplication advantages over the known oligopeptidases. Another advantageof a true proline-specifc endoprotease is that it can be industriallyused to reduce the level of toxic proline rich peptides in glutenwithout a total destruction of the gluten structure. For exampleextruding a wheat gluten paste together with the Aspergillus derivedenzyme will yield a product with some residual textural properties butwith a strongly reduced level of toxic proline rich peptides. To achievethe same reduction of toxic proline rich peptides with a prolyloligopeptidase an almost total pre-hydrolysis with other proteases wouldbe required to achieve the desired peptide lengths below 30 amino acidresidues. Needless to say that this will result in a complete loss ofall relevant physico-chemical properties of the gluten i.e. in a loss ofdough consistency and precluding the baking of loafs with an acceptableshape and volume. Di Cagno et al (Appl. Environ. Microbial., Vol70(2)1088-1096, 2004) report the making of a sourdough bread that iswell tolerated by celiac sprue patients. In their approach the level oftoxic proline rich epitopes was minimised by using a dough prepared witha high proportion of nontoxic flours and fermenting this with selectedlactobacilli for a 24 hours period. Although their results are certainlyof scientific interest, it is obvious that in an industrial environmentfermentation periods as long as 24 hours are economically not feasible.Furthermore their high proportion of nontoxic flours implies that itthere will be a shortage of “regular” gluten so that the volume of thefinal loaf will be limited. Therefore it would be advantageous to availof an economic method enabling the production of 100% wheat bread usingexisting industrial procedures but with limited levels of toxic prolinerich peptides. Such breads can become an important component of dietsaimed at reducing the daily intake of toxic peptides. Consumer groupsfor which such a diet is of special relevance includes infants,youngsters suffering from IBS, elderly people and individuals sufferingfrom diseases and symptoms as described. Although for celiac patients adaily intake of less than 50 milligrams gluten is considered safe, anydiet containing significantly less toxic proline rich peptides thanpresent in the average Western consumption of 13 grams gluten per day islikely to be benificial for the above mentioned consumer groups.

Collectively these considerations indicate novel and considerableadvantages for the A. niger derived enzyme over the enzymes mentioned inthe prior art. Compositions containing the enzymes according to theinvention are advantageously used to reduce or delay glutensensitisation or the phenomena of a disturbed opioid metabolism or thephenomena of IBS. Such compositions can be applied as a digestive aid toachieve a gastrointestinal in situ reduction of the toxic proline richpeptides. Alternatively such compositions can be applied as a processingaid to produce protein hydrolysates without such toxic proline richpeptides. Within the field of protein hydrolysates the brewing of beerprovides a special case in which the application of the A. nigerderived, low pH, proline specific endoprotease offers a surprisingnumber of advantages. WO 02/046381 teaches that a prolyl specificendoprotease applied during either the beer mashing step or before beerfiltration or before beer lagering will reduce the formation of beerhaze. Our present data illustrate that an adequate incubation with thelow pH enzyme will also reduce the level of cereal derived toxicproline-rich proline rich peptides. Surprisingly we have found that thetreatment of beers or other beverages containing cereal proteins withthe proline-specific endoprotease will not only result in reduced hazelevels but will also lead to products that will be safe for peoplesuffering from celiac disease.

Example 1 of the present application shows the acidic pH optimum and anideal temperature optimum of the Aspergillus derived proline specificendoprotease. In Examples 2 and 3 we show that the proline specificendoprotease producible by Aspergillus niger is a true proline specificendoprotease that can cleave large, intact proteins with the sameefficiency as smaller peptides or polypeptides. In fact our dataindicate that the Aspergillus enzyme is a new member of the S28 familyrather than the S9 family to which the known oligopeptidases belong (N.D. Rawlings and A. J. Barrett, Methods in Enzymology, Vol. 244, pp19-61, 1994; N. D. Rawlings and A. J. Barrett, Biochimica & BiophysicaActa 1298(1996) 1-3). We have found that, in contrast with the knownprolyl oligopeptidases, the Aspergillus derived prolyl endoprotease isactive under the acidic conditions in the stomach and shows highefficiencies towards the hydrolysis of large proline rich proteinfragments and polypeptides. Such high efficiencies are illustrated inExamples 4, 5 and 6. In Example 4 we demonstrate that during theproduction of milk protein hydrolysates with Alcalase, an aggressivebroad spectrum protease frequently used in the production of proteinhydrolysates, several peptides incorporating BCM-7 sequences survive thehydrolysis process. However, these peptides rapidly disappear upon anincubation under acid conditions with the Aspergillus derived prolylendoprotease. The data provided in Example reveal the surprising factthat the Aspergillus enzyme cleaves only one of the four prolineresidues available in beta-A2 casein derived BCM-7 molecule. Thisindicates that the incubation of a proline rich-substrate with anyproline-specific protease does not automatically imply the cleavage ofall peptide bonds involving a proline residue, not even under conditionsof a dramatically increased enzyme/substrate ratio. In Example 6 wedemonstrate the efficacy of the Aspergillus derived prolyl endoproteasetowards the gliadin derived 33-mer claimed to be a major epitope inceliac patients. Although again the broad spectrum Alcalase cannotcleave this molecule, neither under alkaline nor under acid conditions,the Aspergillus derived enzyme frequently cleaves the molecule underacid conditions generating 99.5% peptides with a maximum length of 6amino acid residues. So, despite its high efficacy towards praline richpeptides under acid conditions, even the Aspergillus derived enzymeleaves at least 0.5% of a heptamer with the amino acid sequence YPQPQLP.As the sequence PYPQPQLPY is a known celiac patient-specific T cellepitope, this finding illustrates that for suboptimal proline specificenzymes such as the known proline specific oligopeptidases including theenzyme derived from Flavobacterium meningosepticum a realistic in vivoapplication to prevent the formation of toxic peptides from glutenmolecules will proof to be impossible. The latter conclusion isconfirmed by the experiments shown in Examples 7 and 8. In Example 7 wecompare the activity profiles of the A. niger derived praline specificendoprotease with the F. meningosepticum derived praline specificoligopeptidase between pH 2-12. Whereas the A. niger derived enzymeshows activity between pH 2.5 and 7.0, the F. meningosepticum enzymeneeds a pH above 5.0 to become active. In Example 8 we mimic thesituation in the stomach by exposing both praline specific enzymes tolow pH conditions in the absence and presence of the gastric enzymepepsin. Subsequent activity measurements under pH conditions optimal forthe individual enzyme show that the F. meningosepticum enzyme cannotsurvive pH2 or pH 3 conditions. In the presence of pepsin the F.meningosepticum enzyme is already irrecoverably damaged at pH 4. Incontrast, the A. niger derived enzyme survives pH conditions as low aspH 2 and even in the presence of pepsin hereby emphasizing its value forhydrolysing toxic peptides in the stomach. In Example 9 we illustratethat the A. niger derived enzyme can cleave a large number of knownHLA-DQ2 gluten epitopes. Interestingly the positions of observedcleavage sites predict that all T-cell epitopes as known from theliterature are destroyed. In Example 10 we recover gluten epitopes from100% malt beer and 100% wheat bread and demonstrate that we can detectthese epitopes in an antibody assay. In Example 11 we demonstrate thatbeer produced by incorporating the A. niger derived enzyme into theproduction process results in appreciably lowered levels of glutenepitopes. In Example 12 we show that a similar effect can be obtained byincorporating the enzyme into a wheat dough to produce a Dutch tin breadwith lowered levels of gluten epitopes.

Gluten is a non-water soluble compound with a complex three dimensionalstructure. These properties in combination with its proline rich aminoacid composition make the gluten molecules resistant to gastric andintestinal proteolysis. As none of the natural proteolytic activitiessecreted into the gastrointestinal lumen is capable of cleaving peptidebonds involving proline, the use of synergistic exogeneous prolinespecific enzymes makes sense. However, persons suffering from celiacdisease can be extremely sensitive towards the many epitopes that arepresent in gluten. According to the present invention the effect of thenatural digestive proteases can be improved with the Aspergillus derivedprolyl endoprotease, and even further enhancement of the hydrolyticcapacity of this proteolytic mixture is disclosed herein.

It is well known that peptide bonds involving negatively chargedresidues such as Glu (E) and Asp (D) form poor substrates for proteases.Also the natural gastrointestinal proteolytic enzymes cannot cope withthese residues as evidenced by the isolation of the gastric andpancreatic protease resistant peptide WQIPEQSR from gliadin (cf. Shan etal). The latter publication also makes clear that the ubiquitouslypresent glutamine residues (Q) in gluten can be deamidated to glutamateresidues (E) by tissue transglutaminase. Unfortunately thisregiospecific deamidation of gliadin peptides further increases theirimmunogenic potential. Against this background we have been able tocreate an effective enzyme combination existing of an Aspergillusderived praline specific endoprotease with an auxiliary endoprotease toprevent the formation of proline rich toxic proline rich peptides.According to the present invention glutamate-specific endoproteases(EC3.4.21.19) can be used, for example those glutamate-specificendoproteases that are over secreted by a number of food-grademicroorganisms such as Bacillus and Streptomyces. These enzymes can beproduced in an economic and food-grade way. Enzymes which have a safepassage through the stomach, with respect to their enzymatic activityare preferred. In general those enzymes will have an acidic or neutralpH optimum. In combination with the Aspergillus derived prolylendoprotease, this category of glutamate-specific endoproteases isconsidered useful in the production of protein hydrolysates with lowlevels of toxic proline rich peptides.

Quite surprisingly our present research demonstrates that apart from theglutamate-specific endoproteases other endoproteases exist that have asynergistic effect on incubations with the proline specific endoproteasefrom Aspergillus. We conclude that endoproteases (EC 3.4.21-99) capableof cleaving between the amino acid residues Q (glutamine) and L(leucine)are advantageously combined with the proline specific endopeptidase fromAspergillus. Especially endoproteases that have pH optima below pH 5.0and prefer either glutamine or leucine residues in the P1 or in the P1position of the substrate such as the aspergillopepsins (EC 3.4.23.18and 19) and the mucorpepsins (EC 3.4.23.23) are advantageously used.

One application of the enzymes according to the invention is their useas a digestive aid. In this application the compositions of the presentinvention are preferably administered orally, but may also beadministered via other direct routes. The compositions are typicallyadministered to human beings but may also be administered to animals,preferably mammals, to relief the symptoms typical for an increasedgluten sensitivity or a disturbed casein or gluten metabolism or IBS. Intheir application as digestive aid the enzymes according to theinvention may be formulated as a dry powder in, for example, a pill, atablet, a granule, a sachet or a capsule. Alternatively the enzymesaccording to the invention may be formulated as a liquid in, forexample, a syrup or a capsule or may be incorporated into a food productwith a water activity (Aw) below 0.85. The compositions used in thevarious formulations and containing the enzymes according to theinvention may also incorporate at least one compound of the groupconsisting of a physiologically acceptable carrier, adjuvant, excipient,stabiliser, buffer and diluent which terms are used in their ordinarysense to indicate substances that assist in the packaging, delivery,absorption, stabilisation, or, in the case of an adjuvant, enhancing thephysiological effect of the enzymes. The relevant background on thevarious compounds that can be used in combination with the enzymesaccording to the invention in a powdered form can be found in“Pharmaceutical Dosage Forms”, second edition, Volumes 1,2 and 3, ISBN0-8247-8044-2 Marcel Dekker, Inc. Although the enzymes according to theinvention formulated as a dry powder can be stored for rather longperiods, contact with moisture or humid air should be avoided bychoosing suitable packaging such as for example an aluminium blister. Ifformulated in a liquid form, the compounds used for stabilising theenzyme activity and microbial preservation play an important role. Thestabilisation of enzyme activity may require lowered water activities ascan be obtained by the use of polyols such as glycerol or varioussugars. Moreover, divalent cations such as Ca2+ or Mg 2+ are known fortheir stabilising effects as well as reducing agents such as sulphurcontaining amino acids and phenolic compounds such as BHT or propylgallate. Food grade microbial preservation may be achieved using wellknown combinations of low pH conditions or low water activities withsorbate or benzoate or parabenes. Furthermore food grade thickeners suchas a hydrocolloid may be required. A relatively new oral applicationform is the use of gelatin capsule containing a liquid. In thisapplication the liquid is typically an oil or a poly ethlene glycol or alecithin in which the dried enzymes according to the invention can besuspended. Examples of tablet formulations with an improved enzymestability are provided in US2002/0136800.

DESCRIPTION OF THE FIGURES

FIG. 1: A graphic representation of the pH optimum of the A. nigerderived proline specific endoprotease using the synthetic peptideZ-Gly-Pro-pNA as the substrate (cf Example 1).

FIG. 2: SDS-PAGE of intact ovalbumine and a synthetic 27-mer peptideafter incubation with a chromatographically purified A. niger derivedproline specific endoprotease (cf Example 3)

FIG. 3: A graphic representation of the pH optima of the A. niger andthe F. meningosepticum derived proline specific endoprotease (cf Example7).

MATERIALS AND METHODS Materials.

The following enzymes were obtained from Sigma: amyloglucosidase fromAspergillus niger, 300 U/ml, Sigma A-7095; pepsin from porcine stomachmucosa, 2331 U/mg, Sigma P-7012; transglutaminase from Guinea pig, SigmaT-5398. Trypsin solution 2.5% was obtained from Gibco (BRL 25090-028)and Sep-Pak Plus tC18 cartridges, Waters No. 036810 from Waters.Alcalase® AF 2.4 L having an activity of 2.6 AU(A) (Anson UnitAlcalase)Units/gram product was obtained from Novozymes A/S (Bagsvaerd, Denmark).According to Novozymes the details of this activity measurement can befound in Novozymes Analytical Method LUNA #2003-32153-01/SOP No.:EB-SM-0218.02/02).

Synthetic peptides were obtained from Pepscan Systems B.V. (Lelystad,The Netherlands). Chromogenic peptide substrates were obtained eitherfrom Pepscan Systems or from Bachem, Switserland.

Proline-Specific Endoprotease from A. Niger.

Overproduction and chromatographic purification of the proline specificendoprotease from Aspergillus niger was accomplished as described in WO02/45524. The activity of the enzyme (1 unit/10 mg of protein) wastested on the synthetic peptide Z-Gly-Pro-pNA at 37 degrees C. in acitrate/disodium phosphate buffer pH 4.6. The reaction product wasmonitored spectrophotometrically at 405 nM. The activity of thecommercial prolyl oligopeptidase enzyme (as purchased from ICNBiomedicals/MP Biomedicals, Aurora, Ohio, US) was 35 units per mgproduct and was tested on Z-Gly-Pro-pNA at 30 degrees C. in a pH 7.0buffer. The reaction product was monitored spectrophotometrically at 405nM. For both enzymes a unit is defined as the quantity of enzyme thatprovokes the release of 1 μmol of p-nitroanilide per minute under theconditions as specified.

LC/MS Analysis.

HPLC using an ion trap mass spectrometer (Thermo Electront®, Breda, theNetherlands) coupled to a P4000 pump (Thermoquest®, Breda, theNetherlands) was used in characterising the enzymatic proteinhydrolysates produced by the inventive enzyme mixture. The peptides wereseparated using a PEPMAP C18 300A (MIC-15-03-C18-PM, LC Packings,Amsterdam, The Netherlands) column in combination with a gradient of0.1% formic acid in Milli Q water (Millipore, Bedford, Mass., USA;Solution A) and 0.1% formic acid in acetonitrile-(Solution B) forelution. The gradient started at 95% of Solution A and increased to 40%of solution B in 140 minutes and was kept at the latter ratio foranother 5 minutes. The injection volume used was 50 microliters, theflow rate was 50 microliter per minute and the column temperature wasmaintained at 30° C. The protein concentration of the injected samplewas approximately 50 micrograms/milliliter.

Detailed information on the individual peptides was obtained by usingthe “scan dependent” MS/MS algorithm, which is a characteristicalgorithm for an ion trap mass spectrometer.

Full scan analysis was followed by zoom scan analysis for thedetermination of the charge state of the most intense ion in the fullscan mass range. Subsequent MS/MS analysis of the latter ion resulted inpartial peptide sequence information, which could be used for data basesearching using the SEQUEST application from Xcalibur Bioworks(Thermoquest®, Breda, The Netherlands). Data banks used were extractedfrom the OWL fasta databank, available at the NCBI (National Centre forBiotechnology informatics), containing the proteins of interest for theapplication used. In those experiments in which well characterizedprotein substrates such as whey proteins or caseins were measured, theprecision of the analysis technique was increased by omitting thoseMS/MS spectra with a sequence fit of less than 50%.

Angiotensin (M=1295.6) was used to tune for optimal sensitivity in MSmode and for optimal fragmentation in MS/MS mode, performing constantinfusion of 60 microg/ml, resulting in mainly doubly and triply chargedspecies in MS mode, and an optimal collision energy of about 35% inMS/MS mode.

MALDI-TOF

MALDI-TOF was performed using a Voyager De-Pro (Applied Biosystems) massspectrometer. After mixing with the appropriate matrix, peptide sampleswere measured in a linear mode. Masses found via MassLynx software, weresequenced by Post Source Decay (PSD) to confirm the amino acid sequenceof the peptides proposed.

Quantification of Gluten Peptides in Food Samples.

Monoclonal antibodies specific for T cell stimulatory alpha-gliadin,gamma-gliadin and LMW-glutenin peptides are available and wereincorporated in a competition assay for the detection of these peptidesin food samples (E. H. A. Spaenij-Dekking et al., GUT, 53: 1267-1273(2004).

Antibody Based Assays.

For the generation of an antibody-based assay, monoclonal antibodieswere raised in Baib C mice against known T cell stimulatory alpha-,gamma-gliadin and a LMW glutenin peptide. After fusion of the spleens ofthe mice with a mouse myeloma cell line, antibody-producing hybridomaswere obtained. These were cloned by limiting dilution and the monoclonalantibodies secreted by these cells were tested for their use in amonoclonal antibodies competition assay. For each of the specificitiesone or two suitable monoclonal antibodies were selected and the epitopesrecognized by the different monoclonal antibodies were determined (seeTable underneath).

Antibody specificity T cell epitope epitope α-gliadin QLQPFPQPQLPYQPFPQPQ (Glia-alpha2/9) γ-gliadin QPQQPQQSPFQQQRPF QQRPFI (Glia-gamma1)LMW glutenin QPPFSQQQQSPFSQ QSPFS or (Glt-156) PPFSQQ

EXAMPLES

Example 1

The pH and Temperature Optima of the Proline Specific Endoprotease asObtained from A. Niger

The A. niger derived proline specific endoprotease was overexpressed inan A. niger host, isolated and chromatographically purified using thematerials and methods described in WO 02/45524. To establish the pHoptimum of the thus obtained enzyme, buffers with different pH valueswere prepared. Buffers of pH 4.0-4.5-4.8-5.0-5.5 and 6.0 were made using0.05 mol/l Na-acetate and 0.02 M CaCl2; buffers of pH 7.0 and 8.0 weremade using 0.05 M Tris/HCl buffers containing 0.02 M CaCl2. The pHvalues were adjusted using acetic acid and HCl respectively. Thechromogenic synthetic peptide Z-Gly-Pro-pNA was used as the substrate.The buffer solution, the substrate solution and the prolyl endoproteasepre-dilution (in an activity of 0.1 U/mL), were heated to exactly 37.0°C. in a waterbath. After mixing the reaction was followedspectrophotometrically at 405 nm at 37.0° C. for 3.5 min, measuringevery 0.5 min. From the results shown in FIG. 1 it is clear that the A.niger derived proline specific endoprotease has a pH optimum around 4.

Also the temperature optimum of the prolyl endoprotease was established.To that end the purified enzyme preparation was incubated in 0.1 mol/lNa-acetate containing 0.02 mol/l CaCl2 at pH 5.0 for 2 hours atdifferent temperatures using Caseine Resorufine (Roche version 3) as thesubstrate and enzyme activity was quantified by measuring at 574 nm.According to the results obtained the proline specific endoprotease fromA. niger has a temperature optimum around 50 degrees C.

The very acidic pH optimum strongly suggests that the A. niger derivedproline specific endoprotease has ideal properties for industrialapplication as well as for oral consumption as it will be optimallyactive under the acidic conditions preferred for industrial applicationand the conditions prevailing in the stomach and the early part of thesmall intestine. Also the temperature optimum of the enzyme makes theenzyme ideally suitable for both applications.

Example 2 The Enzyme as Obtained from A. Niger Represents a New Class ofProline Specific Enzymes

From the entire coding sequence of the A. niger derived proline specificendoprotease as provided in WO 02/45524 a protein sequence of 526 aminoacids can be determined. The novelty of the enzyme was confirmed byBLAST searches of databases such as SwissProt, PIR and trEMBL. To oursurprise, no clear homology could be detected between the A. nigerenzyme and the known prolyl oligopeptidases. Closer inspection of theamino acid sequence, however, revealed low but significant homology toPro-X carboxypeptidases (EC3.4.16.2), dipeptidyl aminopeptidases I(EC3.4.14.2), and thymus specific serine protease. All of these enzymeshave been assigned to family S28 of serine peptidases. Also the GxSYxGconfiguration around the active site serine is conserved between theseenzymes and the A. niger derived endoprotease. Additionally, members offamily S28 have an acidic pH optimum, have specificity for cleaving atthe carboxy-terminal side of proline residues and are synthesized with asignal sequence and propeptide just like the A. niger derived prolinespecific endoprotease. Also the size of the A. niger enzyme is similarto those the members of family S28. Therefore, the A. niger prolinespecific endoprotease appears to be a member of family S28 of serineproteases rather than the S9 family into which most cytosolic prolyloligopeptidases including the enzyme obtained from Flavobacteriummeningosepticum have been grouped. On the basis of these structural andphysiological features we have concluded that the A. niger enzymebelongs to the S28 rather than the S9 family of serine proteases. Anadditional feature that discriminates the A. niger derived enzyme fromthe prolyl oligopeptidases belonging to the S9 family is the fact that,unlike the cytosolic prolyl endoproteases belonging to the latterfamily, the newly identified A. niger enzyme is secreted into the growthmedium. So far only the basidiomycete Agaricus bisporus (Sattar et al;J. Biochem. 107, 256-261 (1990)) and the non-related ascomyceteAspergillus niger (WO 02/45524) have been shown to produce anextracellular prolyl endopeptidase. However, the enzyme obtained fromthe basidiomycete will not survive pH values below 5 and is thereforefar less suitable for industrial application as well as for oralconsumption.

This is the first report on the isolation and characterization of amember of family S28 from a lower eukaryote.

Example 3 The A. Niger Derived Proline Specific Endoprotease canHydrolyse Large Proteins as Well as Small Peptides and is Thus a TrueEndoprotease

Owing to a specific structural feature, prolyl oligopeptidases belongingto the S9 family cannot digest peptides larger than 30 amino acids. Thislimitation is an obvious disadvantage for an enzyme, which is meant tohydrolyse as quickly and as efficiently as possible all potentialproline rich toxic proline rich peptides. To see if the A. niger derivedproline specific endoprotease exhibits the same limitations with respectto the size of the substrate molecule, we have incubated thechromatographically purified prolyl endopeptidase from A. niger with asmall synthetic peptide and with the large ovalbumine molecule and haveanalysed the hydrolysis products formed by SDS-PAGE. The syntheticpeptide used was a 27-mer of the sequenceNH2-FRASDNDRVIDPGKVETLTIRRLHIPR-COOH and was a gift of the Pepscancompany (Lelystad, The Netherlands). As shown by its amino acidsequence, this peptide contains 2 proline residues, one in the middleand one near the very end of the peptide.

The intact ovalbumine molecule (Pierce Imject, vials containing 20 mgfreeze dried material) consists of 385 amino acids with a molecularweight of 42 750 Da. This molecule contains 14 proline residues, one ofwhich is located at the ultimate C-terminal end of the molecule andcannot be cleaved by a proline specific endoprotease.

Ovalbumin and the oligopeptide were separately incubated at 50° C. withthe purified A. niger derived proline specific endoprotease. At severaltime intervals samples were taken which were the analysed usingSDS-PAGE.

A chromatographically purified A. niger derived proline specificendoprotease with an activity of 4.5 units/ml was diluted 100-fold with0.1 M acetate buffer pH 4 containing 20mM CaCl2. The ovalbumine wasdissolved in acetate buffer pH 4 to a concentration of 1 mg/ml (22 μM).The 27-mer was dissolved in the same buffer to reach a concentration of0.48 mg/ml (152 μM). The molarity of the ovalbumine and the 27-mersolution was chosen in such a way that both solutions contained the samemolarity in cleavable proline residues. Ovalbumine contains 13 potentialproline cleavage sites, whereas the 27-mer peptide has only two. Of bothsubstrate solutions 0.5 nil was incubated with 10 μl (0.45 milliU) ofthe enzyme solution in an Eppendorf thermomixer at 50° C. At severaltime intervals 10 μl samples were withdrawn from the incubation mixtureand kept at 20° C. until SDS-PAGE. All materials used for SDS-PAGE andstaining were purchased from Invitrogen. Samples were prepared using LDSbuffer according to manufacturers instructions and separated on 12%Bis-Tris gels using MES-SDS buffer system according to manufacturersinstructions. Staining was performed using Simply Blue Safe Stain(Collodial Coomassie G250).

As can be seen in FIG. 2 ovalbumine is cleaved by the Aspergillusderived enzyme into a discrete band of about 35 to 36 kD in the first4.75 hours of incubation (lane 3). Prolonged incubation periods resultin further breakdown to smaller products of various molecular weights(lane 7).

The 27-mer peptide is also broken down, as judged by the more faintbands in lanes 4, 6 and 8 as compared to lane 2. The very smallmolecular weight shift of the product (compare lanes 9 and 8) is mostlikely due to cleaving of the arginine residue at the carboxylic end ofthe peptide. The difference is about 200 D (measured using Alphalmager3.3d software on an Alphalmager 2000 system) and arginine has a MW of174. This small molecular weight shift is probably the first step in thebreakdown of the peptide.

The further decay of the product can only be seen by the decrease inintensity of the band on the SDS gel. The products of further decay arenot visible, as in gel staining of components with a MW of about 1000 isnot possible with Coomassie Brillant Blue.

From this experiment it can be concluded that, unlike the known prolyloligopeptidases belonging to the S9 family, the A. niger derived prolinespecific endoprotease has no specific preference for cleaving smallsized peptides over much larger proteins. As such the A. niger derivedenzyme represents a true endoprotease and a preferred enzyme to cleavepotential toxic proline rich proline rich peptides.

Example 4 Beta-Casomorphins in Hydrolysates Formed After Incubation withAlcalase and a Combination of Alcalase Plus Proline SpecificEndoprotease from A. Niger

In analogy with the formation of protease-resistant beta-casomorphinsduring gastro-intestinal proteolysis, we wondered whether during theindustrial production of milk protein hydrolysates a similaraccumulation of BCM-7 related peptide fragments would occur. To that endwe incubated A2 beta-casein isolated from bovine milk with theindustrially frequently used subtilisin Alcalase and with Alcalase plusthe proline specific endoprotease from A. niger. Using LC/MS/MS analysisthe peptides thus formed were analysed.

Bovine milk contains almost 10 grams of beta-caseine per kg of milkrepresenting 28% of all protein present. To facilitate the analysis ofBCM-7 related amino acid. sequences, in this experiment we used aconcentrated preparation (from Sigma) containing a minimum of 90% (A2)beta-casein. The latter product was dissolved in water in aconcentration of 20 grams per litre after which the pH was adjusted to 8using NaOH and Alcalase was added in an amount of 800 microlitre ofenzyme concentrate per litre of casein solution. Incubation was carriedout for 2 hours at 60° C. Then the pH of the solution was lowered till4.5 using citric acid. The solution was then split into two parts: onepart was heated for 5 minutes at 90° C. to inactivate the Alcalase andto the other part the A. niger derived proline specific endoprotease wasadded to obtain an enzyme concentration of 1 unit per gram of caseinpresent (see Materials & Methods section for unit definition).Incubation with the A. niger derived proline specific endoprotease wascontinued for 16 hours at 55° C. followed by another heat treatment toinactivate the proline specific endoprotease. Finally two samples withan estimated beta-casein concentration of 20 mg/ml were supplied forLC/MS/MS analysis. The two samples were centrifuged for 10 minutes at13000 rpm and diluted 20 times in Milli Q prior to LC/MS/MS analysis.LC/MS/MS analysis was carried out as described in the Materials &Methodssection.

Apart from the BCM-7 sequence Tyr-Pro-Phe-Pro-Gly-Pro-Ile at amino acidpositions 60-66 of the beta-casein molecule, the smaller fragments likeTyr-Pro-Phe-Pro (beta-casomorphin (1-4)) and Tyr-Pro-Phe-Pro-Gly(beta-casomorphin (1-5)) at amino acid positions 60-63 and 60-64respectively as well as all larger peptides up to a chain length of 11amino acids (at amino acid positions 60-70) display at least some degreeof opioid activity. The tripetide Tyr-Pro-Phe at position 60-62 has beenreported to have no opioid activity.

For the peptide identification direct LC/MS/MS of the protonatedmolecules was used. The protonated masses of the possibly relevantpeptides are provided in Table 1. All spectra were obtained with acollision amplitude of 35% and a peak width of 3 Da. All experimentaldata are compared with the theoretical fragmentation pattern based onthe so-called B and Y ions: This is the process normally performed usingautomatic data processing.

TABLE 1 Peptide masses analyzed in  LC/MS/MS mode. Peptide amino acidsequence m/z YPFPGPI 790.4 FPGPIPNS 828.4 YPFPGPIP 887.5 VYPFPGPI 889.5VYPFPGPIP 986.5 LVYPFPGPI 1002.5 YPFPGPIPNS 1088.5 LVYPFPGPIP 1099.6VYPFPGPIPN 1100.6 VYPFPGPIPNS 1187.6 YPFPGPIPNSL 1201.7 LVYPFPGPIPN1213.6 VYPFPGPIPNSL 1300.7 LVYPFPGPIPNSL 1413.8

Betacasomorphine amino acid sequences start with tyrosine (Y; residue nr60 of the beta-casein peptide chain) and are given in bold. The m/zvalues represent the protonated molecules of other possibly relevantpeptides. The detection of a proline residue at position 67 indicatesthat the substrate used represents A2 beta-casein.

The results obtained upon LC/MS/MS analysis of the beta-caseinhydrolysates obtained after incubation with either Alcalase or Alcalaseplus proline specific endoprotease are given in Table 2 and can besummarized as follows:

-   The exact beta-casomorphine sequences i.e. YPFPGPI and derivatives    are not present in (A2) beta-casein treated with either Alcalase or    the combination of Alcalase plus the proline specific endoprotease    from A. niger.-   However, two peptides containing the beta-casomorphin sequence are    present in the Alcalase-treated sample i.e. LVYPFPGPIPN and    VYPFPGPIPN.

The intensity of these beta-casomorphin containing sequences aredrastically reduced upon treatment with the proline specificendoprotease from A. niger.

TABLE 2 LC/MS/MS identification of peptides containing the beta-casomorphin (1-7) amino acid sequence Intensity after IntensityAlcalase + Peptide after prol.spec amino acid Alcalase endoproteasesequence m/z treatment treatment YPFPGPI 790.4 — — FPGPIPNS 828.4 — —YPFPGPIP 887.5 — — VYPFPGPI 889.5 — — VYPFPGPIP 986.5 — — LVYPFPGPI1002.5 — — YPFPGPIPNS 1088.5 — — LVYPFPGPIP 1099.6 — — VYPFPGPIPN 1100.6100 10 ⁷ 0.05 10 ⁷ VYPFPGPIPNS 1187.6 — — YPFPGPIPNSL 1201.7 — —LVYPFPGPIPN 1213.6 3.5 10 ⁷ — VYPFPGPIPNSL 1300.7 — — LVYPFPGPIPNSL1413.8 — —

The results clearly indicate that the combination of Alcalase plus theproline specific endoprotease from A. niger destroys all potentialbeta-casomorphin sequences with a high efficiency hereby offering ahydrolysate without potentially toxic proline rich proline richsequences.

After a more precise search among the peptides formed we were able todemonstrate the presence of peptide VYP in the hydrolysate formed by thecombination of the two enzymes. As this peptide could not be traced inthe hydrolysate formed by using just Alcalase, this finding suggestscleavage C-terminal of the proline residue in position 61 of thebeta-casein molecule by the Aspergillus derived enzyme.

Example 5 Peptides Formed Upon the Incubation of the Alcalase FormedPeptide VYPFPGPIPN with the Proline Specific Endoprotease from A. Niger

As shown in Example 4, the hydrolysis of A2 beta-casein with acombination of Alcalase and the proline specific endoprotease from A.niger, effectively removes all potential beta-casomorphin sequences.However, the complexity of the peptides generated did not allow us toestablish at which position the Aspergillus derived enzyme cleaves theAlcalase formed peptide VYPFPGPIPN. To that end a peptide with thisspecific sequence was synthesized and incubated with two concentrationsof the proline specific endoprotease. Subsequent LC/MS/MS analysis ofthe peptides formed revealed the exact cleavage site of the enzyme.

The lyophilised 10-mer (Pepscan Systems; Lelystad, The Netherlands) wasdissolved in a citrate-phosphate buffer pH 4.5 in a concentration of 2mg/ml. To the solution proline specific endoprotease was added inconcentrations of 1 and 10 units per gram of peptide. Incubation tookplace for 4 hours at 55 degrees C. after which a heat treatment of 5minutes at 90 degrees C. was used to inactivate the enzyme. The twosamples were then centrifuged for 10 minutes at 13000 rpm and diluted 20times in Milli Q water prior to LC/MS and LC/MS/MS analysis. The sampleswere first analyzed in LC/MS mode to observe the decrease in intensityof the 10-mer using different amounts of enzyme and to observe whichpeptide masses appeared in the LC/MS ion chromatogram after enzymaticcleavage.

Then direct LC/MS/MS of the protonated molecules of the peptides foundin the LC/MS runs was performed. All spectra were obtained with acollision amplitude of 35% and a peak width of 3 Da. All experimentaldata are compared with the theoretical fragmentation pattern based onthe so-called B and Y ions. This is the process normally performed usingautomatic data processing for identification of peptides, polypeptidesand proteins.

Treatment of the 10-mer VYPFPGPIPN (M=1099.5) with 1 unit/g of proteinalready resulted in total breakdown of the 10-mer into several peptides.The intensity of the protonated molecule, at m/z 1100.5, drops 3 ordersof magnitude. Treatment of the 10-mer with 10 units/g did not result infurther decrease of the intensity of the protonated molecule and also noother peptide masses were found. Upon enzymatic treatment with 1 unit/g4 peptides were formed, with VYP (M=377.2), characterized by m/z 378.2as the most abundant (almost 98%; see Table 3). All four peptides wereanalyzed in LC/MS/MS mode and found to be correct, based on the criteriadescribed above. Table 3: Protonated peptide masses analyzed in LC/MSand LC/MS/MS mode of the 10-mer VYPFPGPIPN M=1099.5. The second columnpresents the m/z values of the protonated molecules, the third columnthe intensity of the protonated molecules observed in LC/MS mode, thefourth column the percentage based on peak area of the protonatedmolecule and the fifth column the position of the peptides found in thetotal amino acid sequence of the 10-mer. It should be emphasized thatusing peak areas of protonated molecules of peptides does not includethe influence of differences in ionization efficiencies.

TABLE 3 Peptides formed upon the incubation of the  BCM-7 related 10-mer VYPFPGPIPN  with the A. niger derived  prolines pecific endoprotease. Peptide Intensity Position in amino acidin LC/MS Percentage total aa sequence m/z mode (%) sequence VYP 378.21 10⁸ 97.7 1-3 VYPF 525.3 3 10⁵ 0.3 1-4 VYPFP 622.4 2 10⁶ 2.0 1-5VYPFPGP 776.4 3 10⁴ 0.03 1-7

However, it can be concluded that the proline specific endoprotease fromA. niger cleaves almost exclusively at the C-terminal side of theproline at position 61 (position 3 for this particular decapeptide. Thecleavage performance is not influenced by increasing enzyme/substrateratios.

As all known beta-casomorphin molecules with opioid activity share theN-terminal sequence YPF, it is evident that the efficient cleavage ofthis sequence between P and F (i.e. carboxy terminal of the prolineresidue at position 61) by the proline specific endoprotease willeffectively inactivate all BCM-7 and BCM-7 related peptides, be it fromthe A1 or from the A2 genetic variant of beta-casein.

The crucial role of the proline residue in position 61 in theinteraction with the mu-receptor was also confirmed in a recent internetpublication (“Sintesi e affinita ai recettori oppiodi di analoghi dellebeta-casomorphine contenenti beta-omo amminoacidi” by the Dipartimentodi Scienza degli Alimenti Universita di Napoli “Frederico II” Facolta diAgraria).

Example 6 Peptides Formed Upon the Incubation of the Gliadin Ferived33-Mer LQLQPFPQPQLPYPQPQLPYPQPQLPYPQPQPF with the Proline SpecificEndoprotease from A. Niger

Treatment of the gastric and pancreatic juices resistant gliadin derived33-mer LQLQPFPQPQLPYPQPQLPYPQPQLPYPQPQPF (M=3911) as described by Shanet al (Science, Vol 297, 27 Sep. 2002) with Alcalase at either pH 8 orpH 5 did not result in any cleavage of the molecule. However, similar tothe situation with the beta-casein derived 10-mer, incubation with 1unit of the proline specific endoprotease from A. niger at pH 5 resultedin total breakdown of the molecule into several peptides. The intensityof the triple protonated 33-mer at m/z 1304.4, drops 3 orders ofmagnitude. No further decrease of the intensity of the protonatedmolecule and also no other peptide masses were observed upon treatmentof the 33-mer with 10 enzyme units per gram of protein.

After enzymatic treatment about 6 main peptides and several minorpeptides were formed, with a peptide characterized by m/z 565.2 as themost abundant. All 6 peptides were analyzed in LC/MS/MS mode and theyall were found to contain proline at the C-terminus, confirming theenzyme's specificity. The major peptide formed is characterized by m/z565.2 (sequence QLP in table 4). Although the C-terminal sequence “LP”could be unabiguously demonstrated for this peptide, the identified masscan theoretically not be formed by endoproteolytic degradation of the33-mer so that there remains some uncertainty regarding the exactN-terminal composition of the peptide. Most probably m/z 565.2 is theN-pyroglutamyl variant of QPQLP (M=581.3), although this was not furtherinvestigated.

Appearance of QPQLP: LQLQPFPQPQLPYPQPQLPYPQPQLPYPQPQPFAppearance of QPQLPYP: LQLQPFPQPQLPYPQPQLPYPQPQLPYPQPQPF.

The LC/MS/MS spectrum of the peptide with m/z 679 could be elucidated tobe PQPQLP. Despite the fact that the nature of the peptide with m/z565.2 was not fully understood, the data obtained clearly demonstratethe preferential cleavage of the proline specific endoprotease fromAspergillus at the C-terminal side of the proline residues at positions12, 19 and 26 (i.e. exclusively between the proline and the tyrosineresidue) of this particular 33-mer. This cleavage pattern is notinfluenced by using higher enzyme/substrate ratios. In table 4 allrelevant information is summarized. The first column specifies thederived peptide sequences, dots used (also in column 5) indicate that noexact starting position of the peptide could be given due to unexplainedmass discrepancies. The second column presents the m/z values of theprotonated molecules, the third column the intensity of the peptidesobserved in LC/MS mode, the fourth column the percentages based on peakarea of the protonated molecule and the fifth column the position of thepeptides identified in the total amino acid sequence.

TABLE 4 Peptides formed upon incubation of the gliadin derived 33-merLQLQPFPQPQLPYPQPQLPYPQPQLPYPQPQPF with the proline specificendoprotease from A. niger. Peptide amino Intensity in Positions inacid sequence m/z LC/MS mode Percentage total aa sequence . . . YP 523.21.9 10⁷ 5.2 . . . 14, . . . 21, . . . 28 YPQPQLP 842.3 1.7 10⁶ 0.513-19, 20-26 QPQP 468.2 3.4 10⁷ 9.3 29-32 PQPQLP 679.2 3.4 10⁷ 9.314-19, 21-26 . . . QLP 565.2 2.4 10⁸ 65.9 . . . 12, . . . 19, . . . 26. . . P 599.2 3.5 10⁷ 9.6

Cleavage of the 33-mer, claimed to be a major epitope in celiacpatients, cannot be accomplished by gastric or pancreatic juices or byincubation with the aggressive broad spectrum protease Alcalase, neitherunder alkaline nor under acid conditions. Nevertheless our resultsindicate an efficient cleavage by the proline specific A. niger derivedendoprotease under acid conditions. The latter cleavage takes placeexclusively between the proline and the tyrosine residues of themolecule and generates 99.5% of peptides with no more than 6 amino acidresidues long. So, despite its high efficacy towards proline richpeptides under acid conditions, even the Aspergillus derived enzymeleaves at least 0.5% of a heptamer with the amino acid sequence YPQPQLP.As the sequence PYPQPQLPY is a known celiac patient-specific T cellepitope, this finding emphasizes once more that for suboptimal prolinespecific enzymes with near neutral pH optima such as the known prolinespecific oligopeptidasesand the enzyme derived from Flavobacteriummeningosepticum, a realistic in vivo application to prevent theformation of toxic peptides from gluten molecules will proof to beimpossible.

Example 7 The pH Activity Spectra of the A. Niger Proline SpecificEndoprotease and the Proline Specific Oligopeptidase from F.Meningosepticum

As demonstrated in Example 1, the pH optimum of the A. niger derivedproline specific endoprotease is about 4.2. In this first test veryacidic pH values were not contemplated so that the behaviour of theenzyme at the pH extremes that can exist in the stomach is notcompletely clear. WO 03/068170 teaches that proline specific proteasessuch as the prolyl oligopeptidase from Flavobacterium meningosepticum orDPPIV from Aspergillus fumigatus or peptidyl dipeptidases fromStreptomyces species present preferred candidates for the in situdegradation of toxic proline rich peptides. Typically all of the latterproteases feature near neutral pH optima that seem to exclude anyhydrolytic activity in the stomach. To demonstrate the difference in pHoptima that exist between the proline specific endoprotease according tothe invention and the prior art enzymes, we compared the pH activityspectra of the Aspergillus derived endoprotease and the Flavobacteriumderived oligopeptidase. The Aspergillus derived endoprotease wasobtained as described in Example 1. The Flavobacterium derivedoligopeptidase was purchased from ICN Biomedicals (35 units/mg; cat no.32082; Ohio, US).

To establish the pH activity spectra of the two enzymes, buffers withdifferent pH values were prepared. Buffers ranging from pH 2.0 to 7.0were prepared using 0.1 mol/l citrate, buffers ranging from pH 6.0 to9.0 were prepared using 0.1 mol/l tris and buffers ranging from pH 8.0to 12.0 were made using 0.2 mol/l glycine. The required pH values wereadjusted using either HCl or NaOH. The chromogenic synthetic peptideZ-Gly-Pro-AMC (Bachem, Switserland) was used as the substrate for bothenzymes. In each well (Costar no. 3631 plates) 85 uL of buffer, 10 uL ofenzyme solution and 5 uL of the substrate (4 mM Z-Gly-Pro-AMC in 60%methanol) was introduced. Final concentration of the A. niger enzyme was32 ug/ml (3.2 milli units/ml), final concentration of the F.meningosepticum enzyme was 0.21 ug/ml (7.4 milli units/ml). After mixingthe reaction was allowed to proceed for 30 minutes at 37.0° C. afterwhich the fluorescence was measured in a CytoFluor multi-well platereader of PerSeptive Biosciences. The relative data as obtained areshown in FIG. 3. The data obtained under these slightly differenttesting conditions confirm the acidic pH optimum of the A. niger derivedproline specific endoprotease as established in Example 1. The data showthat the A. niger enzyme has approx 20% residual activity at pH 2.2 and7.5. The data shown in FIG. 3 also confirm the published pH optimum ofthe F. meningosepticum around pH 7.0. More important in the context ofthe present patent application is that below pH 5.0 the F.meningosepticum enzyme has no activity.

These data show that in contrast with the F. menigosepticum enzyme, theA. niger derived proline specific endoprotease is ideally suited fordeploying its full activity under the acid conditions prevailing in thestomach and part of the duodenum.

Example 8 Stabilities of the A. Niger Proline Specific Endoprotease andthe F. Meningosepticum Proline Specific Oligopeptidase Under Conditionsas Present in the Stomach

Prerequisite for a successful enzyme therapy is the efficientgastrointestinal degradation of toxic proline rich peptides before suchpeptides reach the distal part of the duodenum. This requires that theexogeneous enzyme to be used for the enzyme therapy is a prolinespecific protease that is active during the residence time of dietaryprotein in the stomach and optionally beyond the stomach. To compare theactivities of the A. niger and the F. meningosepticum derived prolinespecific proteases under such “stomach-like” conditions, we assayedtheir residual activities after an incubation at 37 degrees C. fordifferent time periods under different pH conditions and in the presenceand absence of the gasric protease pepsin. Residual enzyme activitieswere assayed using a pH value and a chromogenic peptide optimal for therelevant enzyme i.e. a pH of 7.0 and the Z-Gly-Pro-pNA substrate for theF. meningosepticum enzyme and a pH of 4.0 and an Ala-Ala-Pro-pNAsubstrate for the A. niger enzyme. The A. niger enzyme as used showshigh activity on Ala-Ala-Pro-pNA and some activity (less than 10% of itsactivity on Ala-Ala-Pro-pNA) on the Ala-Ala-Ala-pNA substrate. The A.niger enzyme as used shows no significant activity on otherAla-Ala-X-pNA substrates.

Citrate/HCl buffers of 0.2 mol/l were used for obtaining the requiredacid pH conditions. The dosage of the A. niger derived enzyme was 1.5units/ml, the dosage of the F. meningosepticum enzyme (MP Biochemicals,Ohio, US) 3.3 units/ml (see Materials & Methods section for unitdefinitions). Pepsin (Sigma) was added in a concentration of 180microgram/ml. Pepstatin (Sigma) was added after sampling in aconcentration of 1.67 microgram/ml in order to inactivate the pepsin.Under these conditions pepstatin had no inhibitory effect on the twoproline specific proteases. Residual activities of the two prolinespecific proteases were measured kinetically at 405 nm making use of thesynthetic substrates Ala-Ala-Pro-pNA and Z-Gly-Pro-pNA respectively. Tothat end 200 μL substrate solution (2 mmol/l Z-Gly-Pro-pNA in a 0.05mol/l phosphate buffer pH 7 0 or 1.5 mmol/l Ala-Ala-Pro-pNA in a 0.05mol/l acetic acid buffer pH 4.0) was mixed with a 50 microliter(prediluted 10 to 100×) of the acid/pepsin treated sample in MTP wells.Absorbance was measured kinetically for 10 min at 405 nm at 30° C.making use of a TECAN Genios MTP Reader. (Salzburg, Vienna).

The results depicted in Table 5 show that pH 4 represents the lowerlimit where the F. meningosepticum enzyme can survive. Please note thataccording to the data described in Example 7 the enzyme has no activityunder these pH conditions. After 2 hours at pH 4.0 the enzyme showsapprox 25% residual activity if tested under optimal conditions.However, as soon as pepsin is present, the enzyme is completelyinactivated after 15 minutes at this pH. In contrast with these resultsare the data obtained with the A. niger enzyme. The latter enzymemaintains its full activity at pH values as low as pH 2 and even incombination with pepsin. These results strongly suggest that onlyenzymes with a pH optimum below 5.5 are likely to be active in thestomach so that known proline specific proteases belonging to the enzymeclasses EC 3.4.21.26 (prolyl oligopeptidases), EC 3.4.14.5(dipeptidyl-peptidase IV) and EC 3.4.15.1 (peptidyl-dipeptidase A) donot qualify for degrading proline rich peptides in the stomach.

TABLE 5 Residual enzyme activity of the F. meningosepticumoligopeptidase and the A. niger endoprotease after various incubationperiods under stomach-like conditions Residual enzyme activity ofResidual enzyme activity of Incubation the F. meningosepticum the A.niger endoprotease Conditions oligopeptidase after: after: Pepsin 15 3060 120 15 30 60 120 pH present mins mins mins mins mins mins mins mins 2No − − − − + + + + Yes − − − − + + + + 3 Nos − − − − + + + + Yes − − −− + + + + 4 No + + + +/− + + + + Yes − − − − + + + + + means residualactivity present if tested under conditions optimal for the enzyme, −means no residual activity present if tested under conditions optimalfor the enzyme.

Example 9 Activity of the A. Niger Proline Specific Endoprotease TowardsVarious Gluten Epitopes

A number of publications specify wheat gluten derived peptides that arerecognized by small intestinal T-cells from celiac disease patients. Inthis context peptide binding to HLA-DQ2 molecules is of special interestbecause persons carrying only the HLA-DQ2 haplotype have by far thehighest chance of developing celiac disease (Maki et al.; N Engl J Med.2003 Jun. 19; 348(25):2517-24). All adult HLA-DQ2 patients examinedrespond to the alpha-GLIA sequences Glia-alpha2 and Glia-alpha9(Arentz-Hansen et al, J. Exp. Med. 2000; 6: 337-342). Children withrecent onset celiac disease respond towards the peptides Glia-alpha20,Glia-gamma30, Glt-17, Glt-156 and Glu-21 (Vader et al, Gastroenterology2002; 122:1729-1737). In Example 6 we have already demonstratedsuccessful cleavage of the Glia-alpha2 peptide (PQPQLPYPQPQLPY) by theA. niger derived enzyme. Here we test whether or not the A. niger enzymecan also cleave other relevant wheat gluten derived peptides as well ashomologues of these peptides derived from other cereals.

To that end the relevant peptides were synthesized after which theirpurities were confirmed by rpHPLC and mass spectrometry (MALDI-TOF)according to the procedure described in the Materials & Methods section.Peptide digestions were carried out by mixing 50 microliter of thepeptide solution (1 mg/ml) with 50 microliter of the A. niger enzymesolution containing 0.43 microgram/ml (0.043 milli units) in 50millimol/l ammonium acetate buffer pH 4.5. After various incubationperiods at room temperature 0.5 microliter samples were taken and addedto 9.5 microliter of a matrix solution (1:1 H2O and CH₃CN containing0.2% TFA). After desalting using Dowex ion resin beads, the liquid wasspotted on a MALDI-plate together with some relevant reference peptidesafter which all peptides were analysed. From the data obtained, cleavagesites as indicated in Table 6 could be deduced. Peptides Glt 156 en Gliagamma-2 are 10-mers; Glt 17 is an 8-mer but requires C-terminaleextension by a P and an L residue for optimal binding. Unequivocalcleavage sites are indicated by double vertical lines, cleavage sitesthat were less evident are indicated by a single vertical line. Theknown minimal T-cell epitopes on each peptide are indicated byunderlining. The U's used in Glu-5 represent either a leucine or anisoleucine residue.

From the data obtained it is clear that not only Glia-alpha2 but in factall gluten epitopes relevant for young as well as adult HLA-DQ2 patientsare efficiently hydrolysed by the A. niger derived proline specificprotease. As most of the cleavage sites can be pinpointed to the knownminimal T-cell epitope binding sites, it is likely that exposure of thegluten epitopes to the enzyme will abolish recognition and thuseffectively prevent subsequent T-cell proliferation that ultimatelyleads to the symptoms characteristic for celiac disease patients.

TABLE 6 Cleavage sites of the A.niger derived endoproteasein various known wheat gluten epitopes. Glia - α2 P Q//P Q L P//Y PQ P Q L P Y Glia - α9 Q L Q P//F P//Q P Q L P//Y Glia - α20P F R P//Q Q P//Y P/Q P Q P Q Glia - y1 Q P Q Q P//Q Q S F P//QQ Q R P//F Glia - γ2 Q Q P//Y P Q Q P//Q Q P F P Q Glia - γ30V Q G Q G I I Q P//Q Q P A Q L Glt - 17 Q Q P P//F S Q Q Q Q Q P//L P QGlt-156 Q Q P P//F S Q Q Q Q S P/F S Q Glu - 5Q Q U S Q P//Q U P//Q Q Q Q U P//Q Q P Q Q F Glu- 21Q P Q P//F P//Q Q S E Q S Q Q P//F Q P Q P F

In a similar approach cleavage sites of the A. niger derived enzyme in anumber of oats, barley and rye derived gluten homologues of the wheatgluten epitopes were established (Vader, W et al, Gastroenterology 2003;125:1105-1113). The results obtained (see Table 7) illustrate that theA. niger derived enzyme can not only cleave the wheat gluten epitopesresponsible for celiac disease but also homologues of these peptidesthat are present in oats, barley and rye. As in Table 6, unequivocalcleavage sites are indicated by double lines.

TABLE 7 Cleavage sites of the A.niger derived endoprotease invarious known non-wheat gluten epitopes Gluten Homologue of wheat sourceReference Amino acid sequence gluten epitope Oats Av- QQP//FVQQQQP//FVQGlia-gamma2 gamma2B Oats Av- QQP//FVEQQEQPFVQ Glia-gamma2 gamma2Adeamidated Oats Av- QQP//FVQQQQP//FVQQ Glia-gamma2 gamma2B BarleyHor-alpha2 QQFP//QPQQP//FPQQP Glia-alpha2 Barley Hor-alpha9PQQP//FP//QP//QQPFR//Q Glia-alpha9 Rye Sec-alpha2 QP//FP//QP//QQPFPQSQGlia-alpha2

Example 10 Testing the Recovery of Gluten Epitopes from 100% Malt Beerand 100% Wheat Bread

The extraction procedure as conceived (see Materials & Methods section)was tested in combination with the antibody based assay on a PVPPtreated 100% malt beer (see Example 11) and on a 100% wheat bread sample(see Example 12). According to the results obtained (see Table 8), theextraction procedure in combination with the antibody assay can detectanti-alpha gliadin, anti-gamma gliadin as well as anti-glutenin epitopesin beer as well as bread.

Taken together, the data obtained strongly suggest that the extractionprocedure as applied is suitable for the detection of gluten in both thebeer and bread sample. Based on these results beer and bread samplessubjected to different concentrations of the A. niger derived prolinespecific endoprotease during their processing were more closely examinedin Examples 11 and 12.

TABLE 8 Results of the antibody assay. Two dilutions of the samples weremeasured: 1/16 and 1/64. Anti-alpha gliadin Anti-gamma gliadinAnti-glutenin Sample dilution 1/16 1/64 1/16 1/64 1/16 1/64 Beer >> 24971063 786 166 163 Bread >> 1050 1738 1536 404 215 The results areexpressed as ug/ml of the original sample.

Example 11 Beer Production Involving the Proline Specific Endoproteasefrom A. Niger Leads to Lower Levels of Gluten Epitopes

Beer haze is formed by the association of gluten derived proline richproteins, polypeptides and peptides,with polyphenols that are extractedfrom the cereals (mostly barley) used for beer production. As describedin WO 02/046381 the formation of beer haze can be reduced or preventedby incorporating an acid stable proline specific endoprotease duringeither the mashing, fermentation or lagering phase of beer production.In the conventional beer brewing process haze formation is prevented bya treatment with PVPP, a compound that binds the various polyphenolspresent but with only a minor effect on the level of haze active,proline rich peptides. Because the conventional brewing process does noteliminate the toxic proline rich peptides, celiac patients are notallowed to drink beer.

The purpose of the present study is to establish if addition of the A.niger derived proline specific endoprotease during the beer makingprocess will result in lowered levels of toxic proline rich peptides inthe final beer. If so such beers could be drunk by celiac patients.

Beer production was carried out in a 20 hl pilot plant at IFBM (Nancy,France). The A. niger derived proline specific endoprotease sample usedwas stabilised in 50% glycerol (w/w) and had a final activity of 5units/gram liquid (see Materials & Methods section for the unitdefinition).

In independent production runs, five 100% malt beers were brewed byusing either PVPP (reference) or different quantities of the prolinespecific endoprotease to prevent haze formation. In all experiments themashing protocol used was exactly the same. Depending on the experiment,the proline specific protease was added either at the beginning of themashing process or after the mashing process just before the beerfermentation. In the mashing process three different enzyme dosages weretested, i.e. 2.5, 5.0 and 7.5 enzyme units per kg malt used. Infermentation only a single enzyme dosage was tested, i.e. 0.75 enzymeunits per kg malt added. The reference beer was stabilised with 30grams/hl PVPP added before the beer filtration.

Each brew was produced from 300 kg of barley malt and hop pellets.Mashing conditions of liquid/grist of 3:1 (vol/wt) and pH 5.6 were used.The mashing diagram includes a first step at 45° C. for 20 minutes, asecond step at 64° C. for 15 min and a third step at 76° C. for 25 minand finally a heating to 78° C. Between the steps the heating rate is 1°C. per min. The wort was boiled 90 min. Good trub separations wereperformed on a Whirlpool. The fermentation was carried out with a bottomyeast strain at the pitching rate of 17 10⁶ cells/ml of wort andviability at pitching of about 97%. The fermentation period of 10 daysat 12° C.+/−1° C. was followed by a cold maturation of 5 days at —1°C.+/−1° C. The beer were carbonated at a pressure of 5.2 g/l and, afterbottling, pasteurised at 60° C. for 20 min.

TABLE 9 Different beers and their gluten levels as determined inantibody assays. Beer stabilisation Beer 2 Beer 3 Beer 4 Beer 5 methodBeer 1 fermentation mashing mashing mashing PVPP 30 g/hl Enzyme units/kg0.75 2.5 5.0 7.5 malt used Antibody assays (microgram/ml) Anti-alphagliadin Dilution 1/16 713 15 553 327 199 Dilution 1/64 225 2 163 78 71Anti-gamma gliadin Dilution 1/16 114 8 74 87 42 Dilution 1/64 45 3 26 2022 Anti-glutenin Dilution 1/16 14 4 9 6 8 Dilution 1/64 21 3 13 4 10According to the results the anti-alpha gliadin and anti-gamma gliadinantibodies yield comparable data. The results with the anti-gluteninantibody in this assay are non-conclusive. Evident is that especiallyapplication of the enzyme after the mashing stage leads to very lowlevels of toxic proline rich peptides in the beer. The considerationthat antibody recognition sites have a minimal length of 5 amino acidresidues but a T-cell recognition site requires at least 9 amino acidresidues, makes it even more unlikely that T-cells can recognize theshort peptides generated in the fermentation approach. In fact thesedata strongly indicate that following the above mentioned enzymeapproach beers can be brewed that are safe for celiac patients.

Example 11 Bread Produced by Incorporating the Proline SpecificEndoprotease from A. Niger Into the Dough Results in Lower Levels ofGluten Epitopes

For bread making a dough was prepared from 3500 g of wheat flour (80%Kolibri™ and 20% Ibis™), 1990 ml water (56%), 77 g compressed yeast(2.2%), 70 g salt (2%), 140 mg ascorbic acid (40 ppm) and variousquantities of the A. niger derived enzyme as indicated in Table 10.Quantities of enzymes added were compensated by adding less water to thedough.

The ingredients were mixed into a dough using a Diosnar® spiral mixerfor 2 minutes at speed 1 followed by 6 minutes mixing at speed 2.Doughpieces of 875 g were rounded, proofed for 35 minutes at 34° C. and 85%RH, punched, moulded, panned, proofed for 75 minutes at 38° C. and 87%RH and baked for 20 minutes at 220° C. The evaluation of doughs andfinal bread was carried out by a professional baker. From the results inTable 10 it is clear that addition of the proline-specific endoproteaseapparently did not affect the gluten network and gas-retaining capacityof the dough because the loaf volumes and firmness values were notaffected by enzyme concentrations of 225 units per kg flour or lower. Infact only the addition of higher enzyme dosages imparts negative effectson the dough and generates loafs which would be considered unacceptableby most consumers. Because of the, latter observation, antibody assaydata for breads produced with the highest enzyme concentration were notgenerated. The data depicted in Table 10 show a clear decrease of thetoxic proline rich peptides present in breads produced with an enzymeconcentration around 200 units per kg flour. Very likely this decreasewill proof to be insufficient to allow consumption of such breads byceliac patients. However, the decrease could be large enough to preparefoods with prophylactic benefits for people suffering from an unnoticedceliac disease or from IBS or even for infants with an immature immunesystem.

TABLE 10 Different 100% wheat breads and their gluten levels asdetermined in antibody assays. Enzyme units/kg flour used dosage 0 45225 450 dough good good acceptable unacceptable consistency dough goodgood high very high extensibility loaf volume good large large smallloaf structure good good good very coarse crumb structure Antibodyassays (microgram/ml) Anti-alpha gliadin Dilution 1/16 4231 4231  237not Dilution 1/64 2347 2212  124 determined Anti-gamma gliadin Dilution1/16 1926 1509 1183 not Dilution 1/64 3979 2895  888 determinedAnti-glutenin Dilution 1/16  359  74  98 not Dilution 1/64  232  232 121 determined

1-19. (canceled)
 20. Use of a proline specific endoprotease to producefood which is devoid of celiac related epitopes.
 21. Use according toclaim 19 wherein the celiac related epitopes are gluten epitopes. 22.Use according to claim 21 wherein the gluten epitopes are wheat orbarley epitopes.
 23. Use according to claim 20 wherein the food is beer.24. Use according to claim 23 whereby the proline specific endoproteaseis added after the mashing and before the fermentation step in the beerbrewing process.
 25. Use according to claim 20 wherein the food isbread.
 26. Use according to claim 20 whereby the proline specificendoprotease is an Aspergillus, preferably an Aspergillus niger enzyme.27. Process for the production of food which is devoid of celiac relatedepitopes comprising the use of a proline specific endoprotease. 28.Process according to claim 27 wherein proline specific endoprotease isused at low pH to reduce the level of cereal derived toxic, proline richpeptides.
 29. Beer obtainable by the use of claim 23 that is safe forpeople suffering from celiac disease.
 30. Bread obtainable by the use ofclaim 25 that is safe for people suffering from celiac disease.